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CVE-2026-72375
afs: Fix reinitialisation of the inode, in particular ->lock_work
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem fs/afs. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-72375 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 | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| 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
It seems that initalising afs_vnode::lock_work a single time in the slab's init function isn't sufficient for work_structs. This results in the DEBUG_OBJECTS debugging stuff producing a warning occasionally when running the generic/131 xfstest: ODEBUG: activate not available (active state 0) object: 0000000016d8760f object type: work_struct hint: afs_lock_work+0x0/0x220 WARNING: lib/debugobjects.c:629 at debug_print_object+0x4b/0x90, CPU#3: locktest/7695 ... CPU: 3 UID: 0 PID: 7695 Comm: locktest Tainted: G S 7.1.0-build3+ #2771 PREEMPT ... RIP: 0010:debug_print_object+0x65/0x90 ... Call Trace: <TASK> ? __pfx_afs_lock_work+0x10/0x10 debug_object_activate+0x122/0x170 insert_work+0x25/0x60 __queue_work+0x2e0/0x340 queue_delayed_work_on+0x48/0x70 afs_fl_release_private+0x57/0x70 locks_release_private+0x5c/0xa0 locks_free_lock+0xe/0x20 posix_lock_inode+0x55f/0x5b0 locks_lock_inode_wait+0x81/0x140 ? file_write_and_wait_range+0x50/0x70 afs_lock+0xcd/0x110 fcntl_setlk+0x10d/0x260 do_fcntl+0x24e/0x5b0 __do_sys_fcntl+0x6a/0x90 do_syscall_64+0x11e/0x310 entry_SYSCALL_64_after_hwframe+0x71/0x79 Fix this by reinitialising ->lock_work after allocating an inode. Also, flush ->lock_work when the inode is being evicted to make sure it's not still running.
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.
fs/afs/inode.c
fs/afs/super.c
- What this is
- AFS FILESYSTEMMAINTAINERS section matched on fs/afs/ · linux-afs@lists.infradead.org · Supported
- Kernel module
- kafs
Check it on the machine
grep -w CONFIG_AFS_FS /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.
lsmod | grep -w kafsPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookworm, trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_AFS_FS
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
- not yet assignedsource
- Subsystem
- fs/afs
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.23 | 6.18.40 | 63d3f283858f |
| 2.6.23 | 7.1.5 | ebfd13c0367a |
| 2.6.23 | 7.2 | 5597fbd1e7c1 |
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 via the local VFS file-locking path (fcntl/F_SETLK/F_SETLKW → afs_lock → afs_fl_release_private → queue_delayed_work on vnode->lock_work), not from inbound AFS/RxRPC network packet handling.
- AC:LAttack complexity, low
- An attacker can reliably drive the fault by cycling POSIX locks and inode eviction/reuse on AFS files they control; both sides of the workqueue/slab race are attacker-influenced and freely retryable, matching the intermittent generic/131 locktest reproducer.
- PR:LPrivileges required, low
- On the highest-impact deployment (enterprise/university hosts with AFS already mounted), any unprivileged local user who can open files on that mount can trigger fcntl locking without real root or CAP_SYS_ADMIN in the init namespace.
- UI:NUser interaction, none
- Exploitation requires no action by another user; the attacker directly issues fcntl lock/unlock operations on file descriptors they hold on the shared AFS mount.
- S:UScope, unchanged
- Impact is confined to kernel memory corruption and privilege escalation within the same kernel security boundary; this is not a VM escape, IOMMU bypass, or cross-authority sandbox breakout.
- C:HConfidentiality impact, high
- Stale lock_work reuse and eviction without flush_delayed_work() can leave afs_lock_work operating on freed/reallocated afs_vnode slab memory, a classic use-after-free that can disclose or corrupt adjacent kernel heap contents.
- I:HIntegrity impact, high
- Corrupting or re-queuing a stale delayed_work can corrupt workqueue lists and attacker-controlled vnode fields, providing primitives consistent with arbitrary kernel write and control-flow hijack, not merely a benign warning.
- A:HAvailability impact, high
- Invalid work_struct state triggers kernel warnings/oops in testing and can panic the system when deferred lock work runs against an evicted inode or poisoned slab object during normal lock release.