Look up another CVE · open CVE-2026-72461 in the interactive tracker
CVE-2026-72461
apparmor: fix refcount leak when updating the sk_ctx
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem security/apparmor. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-72461 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Currently update_sk_ctx() transfers the plabel reference, unfortunately it is also unconditionally put in the caller. Ideally we would make the caller conditionally put the reference based on whether it was transferred but for now just fix the bug by getting a reference.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
security/apparmor/af_unix.c
- What this is
- APPARMOR SECURITY MODULEMAINTAINERS section matched on security/apparmor/ · apparmor@lists.ubuntu.com · Supported
Check it on the machine
grep -w CONFIG_SECURITY_APPARMOR /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
Show whether Debian builds this, per release
Debian builds this code. Every release with an answer below compiles the affected file into the kernels it ships. The build rule could not be established for 2 releases, so nothing is claimed about those.
- bookworm, trixie?
- forky, sidy
- ?
- not established - no Makefile entry for the affected file
- y
- built into the kernel image on every flavour - only a patch removes it
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switch
- CONFIG_SECURITY_APPARMOR
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-15 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 6.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- security/apparmor
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.17 | 6.18.40 | 045dbe89ac31 |
| 6.17 | 7.1.5 | b8642f147898 |
| 6.17 | 7.2 | 6d25e7b47616 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The bug is reached only through local Unix-domain socket operations (sendmsg/recvmsg SCM_RIGHTS fd passing, exec file inheritance, or socket file permission revalidation) that invoke AppArmor LSM hooks; it is not reachable via remote network protocols.
- AC:LAttack complexity, low
- An attacker can reliably trigger update_sk_ctx() by creating connected abstract/anonymous AF_UNIX sockets and repeatedly passing the fd across AppArmor confinement boundaries, controlling both endpoints and syscall timing without external race luck.
- PR:LPrivileges required, low
- Only a local unprivileged process subject to AppArmor confinement is required (typical Ubuntu snap/container workloads); no init-namespace root, CAP_MAC_ADMIN, or policy-loading privileges are needed to exercise unix socket mediation.
- UI:NUser interaction, none
- Exploitation is driven entirely by attacker-initiated syscalls and automated fd-receive paths; no additional voluntary action from another human user is required beyond normal daemon recvmsg behavior.
- S:UScope, unchanged
- The flaw corrupts AppArmor label refcounting in the host kernel heap; impact stays within the same kernel security authority and does not by itself cross VM, IOMMU, or container hypervisor boundaries.
- C:HConfidentiality impact, high
- update_sk_ctx() stored plabel in peer_lastupdate without aa_get_label() while the caller aa_put_label(plabel), allowing aa_label objects to be freed while still referenced, creating a heap use-after-free readable via later pointer comparisons and teardown.
- I:HIntegrity impact, high
- Use-after-free/double-free of aa_label structures on socket teardown enables attacker-influenced heap reuse of label objects, which can be leveraged for arbitrary kernel memory corruption and local privilege escalation.
- A:HAvailability impact, high
- Incorrect refcounting causes premature aa_label free and an extra aa_put_label() at sk teardown, provoking refcount underflow, kernel oops, or panic on AppArmor-enabled systems under repeated unix fd passing.