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FreeBSDOperating system

CVE-2026-49413

HIGH · 7.1 CVSS v3.1 Published 2026-06-27
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
73/100
Remediation priority · Elevated
Zero-click 8 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The Linuxulator determined whether a binary was set-user-ID or set-group-ID by checking the P_SUGID process flag. During execve(2), this flag is not yet set at the point where the auxiliary vector is constructed, so AT_SECURE was incorrectly set to zero for set-user-ID and set-group-ID executables. An unprivileged local user can inject a shared library via LD_PRELOAD into a set-user-ID or set-group-ID Linux binary, gaining the privileges of that binary.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

In FreeBSD's Linuxulator, the P_SUGID process flag is checked to determine if a binary is setuid/setgid, but during execve(2) this flag isn't set yet when the auxiliary vector is constructed. This causes AT_SECURE to incorrectly be set to 0 instead of 1, allowing LD_PRELOAD to be honored for privileged Linux binaries and enabling unprivileged users to inject shared libraries and gain the binary's privileges.

MitigationApply the kernel patch to correctly set AT_SECURE during execve in the Linuxulator; until patched, avoid running untrusted setuid/setgid Linux binaries under FreeBSD's Linuxulator or ensure LD_PRELOAD cannot be controlled.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FreeBSDOperating system
Affected:= 14.3= 14.4= 15.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check FreeBSD version
    Run 'uname -a' and look at the release number in the output
    Affected if The version shown is 14.3, 14.4, or 15.0 (e.g., FreeBSD 14.3-RELEASE)
  2. Verify Linuxulator is enabled
    Run 'sysctl compat.linux.osname' or check if the linuxkpi kernel module is loaded via 'kldstat | grep linux'
    Affected if Linuxulator is loaded and active (sysctl returns a value or kldstat shows the linux module)
  3. Identify setuid/setgid Linux binaries
    Search for Linux binaries with setuid/setgid permissions under the Linux emulation directory: 'find /compat/linux -perm -4000 -o -perm -2000' or list all executables in common binary directories
    Affected if Any setuid or setgid Linux binaries exist in /compat/linux (e.g., /compat/linux/usr/bin/su, /compat/linux/bin/ls with special permissions)
  4. Test if LD_PRELOAD is honored for privileged Linux binaries
    As an unprivileged user, create a shared library and attempt to execute a setuid Linux binary with LD_PRELOAD set: 'LD_PRELOAD=/path/to/lib ./setuid_linux_binary'
    Affected if LD_PRELOAD is honored and the library loads (the vulnerability exists); if the binary refuses to load the library (AT_SECURE=1 behavior), the system is not vulnerable to this specific issue

A system is affected if it runs an affected FreeBSD version (14.3, 14.4, or 15.0) with Linuxulator enabled AND has setuid/setgid Linux binaries where unprivileged users can control the LD_PRELOAD environment variable, causing arbitrary library injection.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the kernel patch to correctly set AT_SECURE during execve in the Linuxulator; until patched, avoid running untrusted setuid/setgid Linux binaries under FreeBSD's Linuxulator or ensure LD_PRELOAD cannot be controlled.

Fix this in FreeBSD Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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Scan for this in your stack

Free · runs locally
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-49413 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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