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Known Exploited Vulnerability
9.8
CRITICAL CVSS 3.1
CVE-2025-39682
Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability - [Actively Exploited]
Overview
Description

In the Linux kernel, the following vulnerability has been resolved: tls: fix handling of zero-length records on the rx_list Each recvmsg() call must process either - only contiguous DATA records (any number of them) - one non-DATA record If the next record has different type than what has already been processed we break out of the main processing loop. If the record has already been decrypted (which may be the case for TLS 1.3 where we don't know type until decryption) we queue the pending record to the rx_list. Next recvmsg() will pick it up from there. Queuing the skb to rx_list after zero-copy decrypt is not possible, since in that case we decrypted directly to the user space buffer, and we don't have an skb to queue (darg.skb points to the ciphertext skb for access to metadata like length). Only data records are allowed zero-copy, and we break the processing loop after each non-data record. So we should never zero-copy and then find out that the record type has changed. The corner case we missed is when the initial record comes from rx_list, and it's zero length.

Details
INFO

Published Date :

Sept. 5, 2025, 6:15 p.m.

Last Modified :

Sept. 19, 2026, 4:17 a.m.

Remotely Exploit :

Yes !

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
CISA Notification
CISA KEV (Known Exploited Vulnerabilities)

For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.

Description :

Linux Kernel contains an improper check for unusual or exceptional conditions vulnerability in the TLS receive path which allows a zero-length record retrieved from the rx_list to bypass the intended recvmsg() record-type handling, potentially causing subsequent TLS records to be processed using incorrect zero-copy and queuing assumptions. The impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version.

Required Action :

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Known Ransomware Campaign Use:

Unknown

Notes :

This vulnerability affects an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: ; https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f; https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677; https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9; https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e; https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2025-39682

Impact
Affected Products

The following products are affected by CVE-2025-39682 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
1 Debian debian_linux
: Total Affected Vendor : 2 | Products : 2
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 134c704f-9b21-4f2e-91b3-4a467353bcc0
CVSS 3.1 HIGH [email protected]
CVSS 3.1 CRITICAL 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
Update the Linux kernel to resolve an issue with handling zero-length TLS records during reception.
  • Apply kernel updates to fix TLS record handling.
  • Ensure all systems are running the patched kernel version.
  • Verify TLS functionality after the update.
Public PoC/Exploit Available at Github

CVE-2025-39682 has a 1 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

References
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2025-39682.

URL Resource
https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f Patch
https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e Patch
https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9 Patch
https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843 Patch
https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677 Patch
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html Mailing List Third Party Advisory
https://cert-portal.siemens.com/productcert/html/ssa-032379.html
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39682
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2025-39682 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2025-39682 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Profile Photo
khoatran107/cve-2025-39682

A variant of CVE-2024-58239

Python Shell Makefile C++ C GDB

Updated: 11 months ago
1 stars 0 fork 0 watcher
Born at : Oct. 14, 2025, 7:59 a.m. This repo has been linked 2 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2025-39682 vulnerability anywhere in the article.

  • The Hacker News
CISA Flags Three Linux Kernel Vulnerabilities Exploited in the Wild

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Friday added three security flaws impacting the Linux kernel to its Known Exploited Vulnerabilities (KEV) catalog, citing evidence o ... Read more

Published Date: Sep 19, 2026 (11 hours, 3 minutes ago)
  • TheCyberThrone
CISA KEV Update: Three Linux Kernel Bugs, Acronis Backup and Google Pixel

September 18, 2026 — CISA added three Linux kernel vulnerabilities to its Known Exploited Vulnerabilities (KEV) Catalog. Two additional vulnerabilities affecting Acronis Backup and Google Pixel were a ... Read more

Published Date: Sep 19, 2026 (15 hours, 18 minutes ago)

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2025-39682 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Sep. 19, 2026

    Action Type Old Value New Value
    Changed SSVC {'id': 'CVE-2025-39682', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'active'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-18T19:25:58.427206Z'} {'id': 'CVE-2025-39682', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'active'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-18T00:00:00+00:00'}
  • CVE CISA KEV Update by 9119a7d8-5eab-497f-8521-727c672e3725

    Sep. 18, 2026

    Action Type Old Value New Value
    Added Date Added 2026-09-18
    Added Due Date 2026-09-18
    Added Required Action 2026-09-18
    Added Vulnerability Name 2026-09-18
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Sep. 18, 2026

    Action Type Old Value New Value
    Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39682
    Changed SSVC {'id': 'CVE-2025-39682', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-18T13:57:06.310081Z'} {'id': 'CVE-2025-39682', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'active'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-18T19:25:58.427206Z'}
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Sep. 18, 2026

    Action Type Old Value New Value
    Added Reference https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f
    Added Reference https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e
    Added Reference https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9
    Added Reference https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843
    Added Reference https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677
    Removed Reference https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f
    Removed Reference https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e
    Removed Reference https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9
    Removed Reference https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843
    Removed Reference https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677
    Removed Reference Type https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f Types: Patch
    Removed Reference Type https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e Types: Patch
    Removed Reference Type https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9 Types: Patch
    Removed Reference Type https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843 Types: Patch
    Removed Reference Type https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677 Types: Patch
  • CVE Modified by 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e

    Sep. 18, 2026

    Action Type Old Value New Value
    Added Reference https://cert-portal.siemens.com/productcert/html/ssa-032379.html
    Removed Reference https://cert-portal.siemens.com/productcert/html/ssa-032379.html
  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Sep. 18, 2026

    Action Type Old Value New Value
    Added Reference https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
    Removed Reference https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
    Removed Reference Type https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html Types: Mailing List, Third Party Advisory
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Sep. 18, 2026

    Action Type Old Value New Value
    Added CWE CWE-754
    Changed SSVC {'id': 'CVE-2025-39682', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-10T20:42:07.158655Z'} {'id': 'CVE-2025-39682', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-18T13:57:06.310081Z'}
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jul. 30, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  • CVE Modified by 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e

    Jun. 17, 2026

    Action Type Old Value New Value
    Added Affected [{'vendor': 'Siemens', 'product': 'SIMATIC CN 4100', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': 'V5.0', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}]
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Jun. 17, 2026

    Action Type Old Value New Value
    Added SSVC {'id': 'CVE-2025-39682', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-10T20:42:07.158655Z'}
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jun. 17, 2026

    Action Type Old Value New Value
    Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '84c61fe1a75b4255df1e1e7c054c9e6d048da417', 'lessThan': '2902c3ebcca52ca845c03182000e8d71d3a5196f', 'versionType': 'git'}, {'status': 'affected', 'version': '84c61fe1a75b4255df1e1e7c054c9e6d048da417', 'lessThan': 'c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677', 'versionType': 'git'}, {'status': 'affected', 'version': '84c61fe1a75b4255df1e1e7c054c9e6d048da417', 'lessThan': '3439c15ae91a517cf3c650ea15a8987699416ad9', 'versionType': 'git'}, {'status': 'affected', 'version': '84c61fe1a75b4255df1e1e7c054c9e6d048da417', 'lessThan': '29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e', 'versionType': 'git'}, {'status': 'affected', 'version': '84c61fe1a75b4255df1e1e7c054c9e6d048da417', 'lessThan': '62708b9452f8eb77513115b17c4f8d1a22ebf843', 'versionType': 'git'}], 'programFiles': ['net/tls/tls_sw.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.0'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.0', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.1.149', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.103', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.44', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.16.4', 'versionType': 'semver', 'lessThanOrEqual': '6.16.*'}, {'status': 'unaffected', 'version': '6.17', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/tls/tls_sw.c'], 'defaultStatus': 'affected'}]
  • CVE Modified by 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e

    May. 12, 2026

    Action Type Old Value New Value
    Added Reference https://cert-portal.siemens.com/productcert/html/ssa-032379.html
  • Modified Analysis by [email protected]

    Mar. 17, 2026

    Action Type Old Value New Value
    Changed Reference Type CVE: https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html Types: Third Party Advisory CVE: https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html Types: Mailing List, Third Party Advisory
  • Initial Analysis by [email protected]

    Jan. 27, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
    Added CWE NVD-CWE-Other
    Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.2 up to (excluding) 6.6.103 *cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.12.44 *cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.16.4 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.0 up to (excluding) 6.1.149
    Added CPE Configuration OR *cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677 Types: Patch
    Added Reference Type CVE: https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html Types: Third Party Advisory
  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Nov. 03, 2025

    Action Type Old Value New Value
    Added Reference https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Sep. 05, 2025

    Action Type Old Value New Value
    Added Description In the Linux kernel, the following vulnerability has been resolved: tls: fix handling of zero-length records on the rx_list Each recvmsg() call must process either - only contiguous DATA records (any number of them) - one non-DATA record If the next record has different type than what has already been processed we break out of the main processing loop. If the record has already been decrypted (which may be the case for TLS 1.3 where we don't know type until decryption) we queue the pending record to the rx_list. Next recvmsg() will pick it up from there. Queuing the skb to rx_list after zero-copy decrypt is not possible, since in that case we decrypted directly to the user space buffer, and we don't have an skb to queue (darg.skb points to the ciphertext skb for access to metadata like length). Only data records are allowed zero-copy, and we break the processing loop after each non-data record. So we should never zero-copy and then find out that the record type has changed. The corner case we missed is when the initial record comes from rx_list, and it's zero length.
    Added Reference https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f
    Added Reference https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e
    Added Reference https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9
    Added Reference https://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843
    Added Reference https://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CVSS
Vulnerability Scoring Details
Base CVSS Score: 9.8
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact