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CVE-2026-72162
ocfs2: fix UBSAN array-index-out-of-bounds in ocfs2_sum_rightmost_rec
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem fs/ocfs2. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-72162 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
[BUG] On-disk corruption setting l_next_free_rec to 0 in an inode's embedded extent list triggers a UBSAN panic on the next write to that file. [CAUSE] ocfs2_sum_rightmost_rec() computes i = le16_to_cpu(el->l_next_free_rec) - 1 and accesses el->l_recs[i] without validating i. When l_next_free_rec is 0, i becomes -1; when l_next_free_rec exceeds l_count, i falls past the end of the array. Either case violates the __counted_by_le(l_count) annotation on l_recs[] and triggers UBSAN. [FIX] Validate the inode's embedded extent list when the inode is read, in ocfs2_validate_inode_block(): l_count must be non-zero and no larger than the inode block can hold, and l_next_free_rec must not exceed l_count. A corrupt list is rejected at read time, before the b-tree code can index l_recs[] out of bounds.
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/ocfs2/inode.c
- What this is
- ORACLE CLUSTER FILESYSTEM 2 (OCFS2)MAINTAINERS section matched on fs/ocfs2/ · ocfs2-devel@lists.linux.dev · Supported
- Kernel module
- ocfs2
Check it on the machine
grep -w CONFIG_OCFS2_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 ocfs2Prints 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_OCFS2_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
- 0.16%, higher than 4.9% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- fs/ocfs2
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.22 | 6.18.40 | 671889c553ea |
| 2.6.22 | 7.1.5 | 858aa4965ffa |
| 2.6.22 | 7.2 | 452a8467be81 |
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 local VFS write paths on a mounted OCFS2 volume (write/mmap extending allocation), not from network packet handling or remote protocols; exploitation requires local syscall access to a mounted filesystem.
- AC:LAttack complexity, low
- An attacker can reliably craft on-disk inode metadata (e.g., l_next_free_rec=0) in an OCFS2 image and trigger btree growth with a normal extending write; syzkaller reproduced this deterministically without races or victim-specific timing.
- PR:LPrivileges required, low
- Full exploitation requires mounting a crafted OCFS2 image and writing to it; CAP_SYS_ADMIN for mount/loop setup is obtainable by an unprivileged user via user namespaces, matching the low-privilege bar used for comparable OCFS2 corruption CVEs.
- UI:NUser interaction, none
- No victim interaction is required when the attacker crafts the corrupt image, mounts it (including via user namespace), and performs the triggering write themselves; no third party must open files or take other actions.
- S:UScope, unchanged
- Impact is confined to kernel memory/filesystem integrity on the host processing the corrupt OCFS2 metadata; it does not cross VM, container, or IOMMU security boundaries into another authority.
- C:HConfidentiality impact, high
- The flaw is an out-of-bounds read of extent records from attacker-controlled on-disk fields; even when UBSAN traps, the invalid index access can expose adjacent inode metadata and is classed as information-disclosure-capable memory corruption.
- I:HIntegrity impact, high
- The out-of-bounds sum feeds btree growth/shift logic that writes derived cluster counts and tree pointers back to disk, enabling attacker-influenced metadata corruption beyond the immediate read primitive.
- A:HAvailability impact, high
- On UBSAN-enabled kernels the invalid array index triggers a kernel panic on write; even without UBSAN, corrupt btree updates from the bad sum can crash or destabilize the system, satisfying high availability impact.