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CVE-2026-74350

ocfs2: validate fast symlink target during inode read

9.8 EPSS 0.6% AV:N

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-2026-74350 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

ocfs2_validate_inode_block() already rejects several inconsistent self-contained dinodes before they are exposed to the rest of the filesystem. Fast symlinks need the same treatment. A zero-cluster symlink is treated as a fast symlink and later read through page_get_link() and ocfs2_fast_symlink_read_folio(). That path uses strnlen() on the inline payload and then copies len + 1 bytes into the folio. If a corrupt dinode stores an i_size that does not fit the inline area or omits the terminating NUL at i_size, that copy reads past the end of the inode block buffer. Reject zero-cluster symlink dinodes whose i_size exceeds the inline fast-symlink capacity or whose inline payload is not NUL-terminated exactly at i_size when the inode block is validated. This keeps malformed fast symlinks from reaching the read path. Validation reproduced this kernel report: KASAN use-after-free in ocfs2_fast_symlink_read_folio+0x12c/0x1f0 RIP: 0033:0x7f5c6d859aa7 Read of size 3905 Call trace: dump_stack_lvl+0x66/0xa0 (?:?) print_report+0xce/0x630 (?:?) ocfs2_fast_symlink_read_folio+0x12c/0x1f0 (fs/ocfs2/inode.c:?) srso_alias_return_thunk+0x5/0xfbef5 (?:?) __virt_addr_valid+0x19f/0x330 (?:?) kasan_report+0xe0/0x110 (?:?) kasan_check_range+0x105/0x1b0 (?:?) __asan_memcpy+0x23/0x60 (?:?) filemap_read_folio+0x27/0xe0 (?:?) filemap_read_folio+0x35/0xe0 (?:?) do_read_cache_folio+0x138/0x230 (?:?) __page_get_link+0x26/0x110 (?:?) page_get_link+0x2e/0x70 (?:?) vfs_readlink+0x15e/0x250 (?:?) touch_atime+0x4d/0x370 (?:?) do_readlinkat+0x186/0x200 (?:?) do_user_addr_fault+0x65a/0x890 (?:?) __x64_sys_readlink+0x46/0x60 (?:?) do_syscall_64+0x115/0x6a0 (arch/x86/entry/syscall_64.c:87) entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)

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 ocfs2

Prints 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

Debian tracker CVE record NVD kernel CNA record

Signals

Published: 2026-08-15 (2 months ago)source
CVSS: 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it
Attack vector: network (AV:N)source
EPSS: 0.63%, higher than 49.2% 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
3.5	6.18.57	d94bf50756d7
3.5	7.1.5	f9e2cb692b77
3.5	7.2	e234973f286e

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:NAttack vector, network: OCFS2 cluster nodes commonly NFS-export shared LUNs; nfsd READLINK reaches vfs_readlink→page_get_link→ocfs2_fast_symlink_read_folio on a forged zero-cluster symlink dinode on the volume, giving a remote network attack path without a local syscall.
AC:LAttack complexity, low: A forged dinode fully controls i_size and inline bytes; strnlen() bounded only by ocfs2_fast_symlink_chars() then memcpy_to_folio() copies len+1 past the inode buffer_head (KASAN read ~3905), deterministically and without races.
PR:NPrivileges required, none: Triggering needs only permission to read the symlink: a remote NFS client on an exported share, or any unprivileged local/cluster user; planting the malformed dinode uses attacker-controlled on-disk metadata on shared storage, not init-namespace root on the victim.
UI:NUser interaction, none: Once the corrupt fast symlink exists on a mounted/exported volume, readlink(2), NFS READLINK, or path lookup via get_link automatically pulls the inline target through ocfs2_fast_symlink_read_folio with no further deliberate victim action.
S:UScope, unchanged: Impact stays within the host kernel parsing the OCFS2 symlink (memory disclosure/crash/privilege escalation on the server); no VM escape, IOMMU bypass, or cross-authority scope change.
C:HConfidentiality impact, high: memcpy_to_folio() performs an out-of-bounds read up to ~3900 bytes past the inode block buffer (KASAN UAF/slab read of size 3905); OOB/UAF kernel reads enable arbitrary adjacent-heap disclosure.
I:HIntegrity impact, high: The same unvalidated strnlen/memcpy path corrupts kernel memory semantics (KASAN UAF) and, per kernel CNA guidance, UAF/OOB reads adjacent slab objects can be leveraged into write/control-flow primitives via heap grooming.
A:HAvailability impact, high: KASAN reports use-after-free in ocfs2_fast_symlink_read_folio during the over-wide memcpy; such kernel memory faults typically oops/panic the host, fully denying availability.