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7.1
HIGH CVSS 3.1
CVE-2026-49421
unlinkat(2) ignores AT_RESOLVE_BENEATH flag
Overview
Description

The kernel function that implements unlinkat(2) and funlinkat(2) validated the AT_RESOLVE_BENEATH flag but failed to pass it through to the underlying path lookup. The flag was silently dropped, so path resolution was not actually restricted. A process that uses AT_RESOLVE_BENEATH with unlinkat(2) or funlinkat(2) to confine path resolution can in fact resolve paths above the starting directory. A caller relying on this flag for path containment may delete files outside the intended directory tree.

Details
INFO

Published Date :

Aug. 19, 2026, 6:17 a.m.

Last Modified :

Sept. 1, 2026, 8:20 p.m.

Remotely Exploit :

No

Source :

[email protected]
Impact
Affected Products

The following products are affected by CVE-2026-49421 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 Freebsd freebsd
: 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 134c704f-9b21-4f2e-91b3-4a467353bcc0
CVSS 3.1 HIGH 134c704f-9b21-4f2e-91b3-4a467353bcc0
Solution
Apply kernel updates to fix the AT_RESOLVE_BENEATH flag issue for unlinkat and funlinkat.
  • Update the system kernel to the latest patched version.
  • Verify the AT_RESOLVE_BENEATH flag behavior.
  • Review file deletion operations for potential policy violations.
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-2026-49421.

URL Resource
https://security.freebsd.org/advisories/FreeBSD-SA-26:42.unlinkat.asc Vendor Advisory
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-49421 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-2026-49421 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-2026-49421 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-2026-49421 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.

  • Initial Analysis by [email protected]

    Sep. 01, 2026

    Action Type Old Value New Value
    Added CPE Configuration OR *cpe:2.3:o:freebsd:freebsd:15.0:p1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p2:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p2:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p3:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p4:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p5:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p6:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p7:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p8:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:rc1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p3:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p9:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p4:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p10:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p11:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:p1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:p2:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p5:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p6:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p12:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p13:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:p3:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:p4:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p7:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p8:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p14:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:p5:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p9:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.1:rc2:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:p6:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p10:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.1:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.1:rc3-p1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p15:*:*:*:*:*:*
    Added Reference Type FreeBSD: https://security.freebsd.org/advisories/FreeBSD-SA-26:42.unlinkat.asc Types: Vendor Advisory
  • CVE Modified by [email protected]

    Aug. 26, 2026

    Action Type Old Value New Value
    Added Reference https://security.freebsd.org/advisories/FreeBSD-SA-26:42.unlinkat.asc
    Removed Reference https://security.freebsd.org/advisories/FreeBSD-SA-26:42.unlinkat.asc
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Aug. 26, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
    Added SSVC {'id': 'CVE-2026-49421', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-26T17:44:11.280156Z'}
  • New CVE Received by [email protected]

    Aug. 19, 2026

    Action Type Old Value New Value
    Added Affected [{'vendor': 'FreeBSD', 'modules': ['libalias'], 'product': 'FreeBSD', 'versions': [{'status': 'affected', 'version': '15.1-RELEASE', 'lessThan': 'p1', 'versionType': 'release'}, {'status': 'affected', 'version': '15.0-RELEASE', 'lessThan': 'p11', 'versionType': 'release'}, {'status': 'affected', 'version': '14.4-RELEASE', 'lessThan': 'p7', 'versionType': 'release'}, {'status': 'affected', 'version': '14.3-RELEASE', 'lessThan': 'p16', 'versionType': 'release'}], 'defaultStatus': 'unknown'}]
    Added Description The kernel function that implements unlinkat(2) and funlinkat(2) validated the AT_RESOLVE_BENEATH flag but failed to pass it through to the underlying path lookup. The flag was silently dropped, so path resolution was not actually restricted. A process that uses AT_RESOLVE_BENEATH with unlinkat(2) or funlinkat(2) to confine path resolution can in fact resolve paths above the starting directory. A caller relying on this flag for path containment may delete files outside the intended directory tree.
    Added CWE CWE-273
    Added Reference https://security.freebsd.org/advisories/FreeBSD-SA-26:42.unlinkat.asc
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: 7.1
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact