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7.8
HIGH CVSS 3.1
CVE-2026-74496
fou: Fix use-after-free in fou_create()
Overview
Description

In the Linux kernel, the following vulnerability has been resolved: fou: Fix use-after-free in fou_create() fou_create() publishes struct fou through sk_user_data before adding the new FOU port to the per-netns list. If fou_add_to_port_list() fails, the error path frees fou while it is still reachable through sk_user_data. A concurrent receive can then dereference the freed object in fou_from_sock(). This ordering issue was previously noted in the linked discussion. The failure is reachable when local port 0 is requested. Each socket binds to a different ephemeral port, but fou_cfg_cmp() compares the requested port 0 and reports -EALREADY once an entry already exists. Release the tunnel socket before freeing fou so sk_user_data is cleared first, and defer reclamation with kfree_rcu() to protect concurrent RCU readers. This matches the lifetime handling in fou_release().

Details
INFO

Published Date :

Aug. 15, 2026, 1:17 p.m.

Last Modified :

Oct. 3, 2026, 11:17 a.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Impact
Affected Products

The following products are affected by CVE-2026-74496 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
: Total Affected Vendor : 1 | Products : 1
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 3.1 HIGH 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
Fix use-after-free by releasing tunnel socket before freeing fou.
  • Release tunnel socket before freeing fou.
  • Defer reclamation with kfree_rcu().
  • Apply the provided kernel patch.
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-2026-74496.

URL Resource
https://git.kernel.org/stable/c/0ee628a58d83e571f36ec9f07624d6845e420c50
https://git.kernel.org/stable/c/58835985c035a8333742f829ad7e0889a082f9d3
https://git.kernel.org/stable/c/9042867d4701728f0c6527215b11471759904d8f
https://git.kernel.org/stable/c/99f4d3120b244f92e5df787152041296a2860cb5
https://git.kernel.org/stable/c/a28d8903bfe76089ea4bbdbff9976965f9ef8107
https://git.kernel.org/stable/c/a6fca682cfa2041e31aa72cc397c4a1406eb7468
https://git.kernel.org/stable/c/b14361aca6350ff7907b0e9903c7b94dc7d5d4a0
https://git.kernel.org/stable/c/b3f9c3e60aa25453774f899d25b5e61dd0bec1d5
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-74496 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-2026-74496 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).

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

The following list is the news that have been mention CVE-2026-74496 vulnerability anywhere in the article.

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-2026-74496 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 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Oct. 03, 2026

    Action Type Old Value New Value
    Added Affected Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/74xxx/CVE-2026-74496.json">CVE-2026-74496</a>
    Added Reference https://git.kernel.org/stable/c/0ee628a58d83e571f36ec9f07624d6845e420c50
    Added Reference https://git.kernel.org/stable/c/99f4d3120b244f92e5df787152041296a2860cb5
    Added Reference https://git.kernel.org/stable/c/a6fca682cfa2041e31aa72cc397c4a1406eb7468
    Added Reference https://git.kernel.org/stable/c/b3f9c3e60aa25453774f899d25b5e61dd0bec1d5
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Sep. 21, 2026

    Action Type Old Value New Value
    Added Affected Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/74xxx/CVE-2026-74496.json">CVE-2026-74496</a>
    Added Reference https://git.kernel.org/stable/c/58835985c035a8333742f829ad7e0889a082f9d3
    Added Reference https://git.kernel.org/stable/c/9042867d4701728f0c6527215b11471759904d8f
    Added Reference https://git.kernel.org/stable/c/a28d8903bfe76089ea4bbdbff9976965f9ef8107
    Added Reference https://git.kernel.org/stable/c/b14361aca6350ff7907b0e9903c7b94dc7d5d4a0
    Removed Reference https://git.kernel.org/stable/c/a28d8903bfe76089ea4bbdbff9976965f9ef8107
    Removed Reference https://git.kernel.org/stable/c/b14361aca6350ff7907b0e9903c7b94dc7d5d4a0
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Aug. 17, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
    Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '23461551c00628c3f3fe9cf837bf53cf8f212b63', 'lessThan': 'a28d8903bfe76089ea4bbdbff9976965f9ef8107', 'versionType': 'git'}, {'status': 'affected', 'version': '23461551c00628c3f3fe9cf837bf53cf8f212b63', 'lessThan': 'b14361aca6350ff7907b0e9903c7b94dc7d5d4a0', 'versionType': 'git'}], 'programFiles': ['net/ipv4/fou_core.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.18'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.18', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.8', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc6', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/ipv4/fou_core.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '23461551c00628c3f3fe9cf837bf53cf8f212b63', 'lessThan': 'a28d8903bfe76089ea4bbdbff9976965f9ef8107', 'versionType': 'git'}, {'status': 'affected', 'version': '23461551c00628c3f3fe9cf837bf53cf8f212b63', 'lessThan': 'b14361aca6350ff7907b0e9903c7b94dc7d5d4a0', 'versionType': 'git'}], 'programFiles': ['net/ipv4/fou_core.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.18'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.18', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.8', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/ipv4/fou_core.c'], 'defaultStatus': 'affected'}]
  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Aug. 15, 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': '23461551c00628c3f3fe9cf837bf53cf8f212b63', 'lessThan': 'a28d8903bfe76089ea4bbdbff9976965f9ef8107', 'versionType': 'git'}, {'status': 'affected', 'version': '23461551c00628c3f3fe9cf837bf53cf8f212b63', 'lessThan': 'b14361aca6350ff7907b0e9903c7b94dc7d5d4a0', 'versionType': 'git'}], 'programFiles': ['net/ipv4/fou_core.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '3.18'}, {'status': 'unaffected', 'version': '0', 'lessThan': '3.18', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.8', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc6', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/ipv4/fou_core.c'], 'defaultStatus': 'affected'}]
    Added Description In the Linux kernel, the following vulnerability has been resolved: fou: Fix use-after-free in fou_create() fou_create() publishes struct fou through sk_user_data before adding the new FOU port to the per-netns list. If fou_add_to_port_list() fails, the error path frees fou while it is still reachable through sk_user_data. A concurrent receive can then dereference the freed object in fou_from_sock(). This ordering issue was previously noted in the linked discussion. The failure is reachable when local port 0 is requested. Each socket binds to a different ephemeral port, but fou_cfg_cmp() compares the requested port 0 and reports -EALREADY once an entry already exists. Release the tunnel socket before freeing fou so sk_user_data is cleared first, and defer reclamation with kfree_rcu() to protect concurrent RCU readers. This matches the lifetime handling in fou_release().
    Added Reference https://git.kernel.org/stable/c/a28d8903bfe76089ea4bbdbff9976965f9ef8107
    Added Reference https://git.kernel.org/stable/c/b14361aca6350ff7907b0e9903c7b94dc7d5d4a0
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: 7.8
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact