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============================================================================= FreeBSD-SA-26:45.audit Security Advisory
The FreeBSD Project

Topic: Incorrect audit records for ptrace(2) syscall requests

Category: core
Module: audit
Announced: 2026-06-30
Credits: Kyle Evans
Affects: All supported versions of FreeBSD.
Corrected: 2026-06-30 17:20:16 UTC (stable/15, 15.1-STABLE)
2026-06-30 17:22:04 UTC (releng/15.1, 15.1-RELEASE-p1)
2026-06-30 17:21:32 UTC (releng/15.0, 15.0-RELEASE-p11)
2026-06-30 17:19:56 UTC (stable/14, 14.4-STABLE)
2026-06-30 17:21:05 UTC (releng/14.4, 14.4-RELEASE-p7)
2026-06-30 17:20:38 UTC (releng/14.3, 14.3-RELEASE-p16)
CVE Name: CVE-2026-49426

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the following sections, please visit <URL:https://security.FreeBSD.org/>.

I. Background

The audit(4) facility allows a system administrator to audit
security-relevant events, including system calls.

The ptrace(2) system call permits a debugger to execute arbitrary system
calls in a target process via the PT_SC_REMOTE operation, and the
audit(4) facility records the outcome of such remotely executed system
calls.

II. Problem Description

When auditing a system call executed via ptrace(PT_SC_REMOTE), the
kernel passed the return value of an internal setup function to AUDIT_SYSCALL_EXIT() rather than the actual result of the executed
system call. As a result, committed audit records for system calls
which returned an error do not reflect the true outcome of the
operation. That is, they indicate that the operation succeeded when
it in fact failed.

III. Impact

Audit records for system calls executed via ptrace(PT_SC_REMOTE) may
show an incorrect error status. An attacker with the ability to debug
a process could use this to produce misleading audit trails, potentially undermining audit-based Intrusion Detection Systems (IDS).

IV. Workaround

No workaround is available. Systems that do not use audit(4) are not
affected.

V. Solution

Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date, and
reboot the system.

Perform one of the following:

1) To update your vulnerable system installed from base system packages:

Systems running a 15.0-RELEASE or later version of FreeBSD on the amd64 or arm64 platforms, which were installed using base system packages, can be updated via the pkg(8) utility:

# pkg upgrade -r FreeBSD-base
# shutdown -r +10min "Rebooting for a security update"

2) To update your vulnerable system installed from binary distribution sets:

Systems running a RELEASE version of FreeBSD on the amd64 or arm64 platforms which were not installed using base system packages can be updated via the freebsd-update(8) utility:

# freebsd-update fetch
# freebsd-update install
# shutdown -r +10min "Rebooting for a security update"

3) To update your vulnerable system via a source code patch:

The following patches have been verified to apply to the applicable
FreeBSD release branches.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

# fetch https://security.FreeBSD.org/patches/SA-26:45/audit.patch
# fetch https://security.FreeBSD.org/patches/SA-26:45/audit.patch.asc
# gpg --verify audit.patch.asc

b) Apply the patch. Execute the following commands as root:

# cd /usr/src
# patch -E -p0 < /path/to/patch

c) Recompile your kernel as described in <URL:https://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
system.

VI. Correction details

This issue is corrected as of the corresponding Git commit hash in the following stable and release branches:

Branch/path Hash Revision
- ------------------------------------------------------------------------- stable/15/ ec1989960781 stable/15-n284331 releng/15.1/ 8666a62872de releng/15.1-n283576 releng/15.0/ f887a2c04c9e releng/15.0-n281078 stable/14/ 1763deb84ba9 stable/14-n274456 releng/14.4/ d68c2e77d70c releng/14.4-n273738 releng/14.3/ 8b11e7df3a62 releng/14.3-n271538
- -------------------------------------------------------------------------

Run the following command to see which files were modified by a
particular commit:

# git show --stat <commit hash>

Or visit the following URL, replacing NNNNNN with the hash:

<URL:https://cgit.freebsd.org/src/commit/?id=NNNNNN>

To determine the commit count in a working tree (for comparison against
nNNNNNN in the table above), run:

# git rev-list --count --first-parent HEAD

VII. References

<URL:https://www.cve.org/CVERecord?id=CVE-2026-49426>

The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-26:45.audit.asc> -----BEGIN PGP SIGNATURE-----

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