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CVE-2026-72355
netfs: Fix barriering when walking subrequest list
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem fs/netfs. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-72355 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 | 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
Fix the barriering used when walking the subrequest list in retry as there's a possibility of seeing a subreq that's just been added by the application thread.
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/netfs/read_retry.c
fs/netfs/write_retry.c
- What this is
- FILESYSTEMS [NETFS LIBRARY]MAINTAINERS section matched on fs/netfs/ · netfs@lists.linux.dev · Supported
- Kernel module
- netfs
Check it on the machine
grep -w CONFIG_NETFS_SUPPORT /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 netfsPrints 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 as a loadable module. Every release with an answer below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookworm?
- trixie, forky, sidm
- ?
- not established - no Makefile entry for the affected file
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
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_NETFS_SUPPORT
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
- 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
- 0.65%, higher than 50.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- fs/netfs
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.10 | 6.18.53 | 4cca4b44e561 |
| 6.10 | 7.1.5 | be47c0472506 |
| 6.10 | 7.2 | 5c6ce05e4065 |
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
- The flaw is in the netfs client retry path used by SMB/CIFS, Ceph, NFS+fscache, and AFS; a remote malicious or MITM file server can trigger NEED_RETRY via short/error network responses during client read/write I/O.
- AC:LAttack complexity, low
- The attacker controls both sides of the race by timing retry-inducing server responses and issuing concurrent reads/writes (multiple threads/fds); no victim-specific memory layout or rare uncontrollable state is required beyond normal mounted-FS I/O.
- PR:NPrivileges required, none
- No local privileges on the victim are required; a remote attacker operating a malicious or compromised SMB/Ceph/NFS/AFS server can exploit any client with an active mount performing file I/O, without shell or admin access on the client.
- UI:NUser interaction, none
- On commonly pre-mounted enterprise/automounted network shares, kernel readahead and writeback can reach the buggy retry path without additional victim action at exploitation time beyond existing background file access.
- S:UScope, unchanged
- Exploitation corrupts the client kernel heap and enables local privilege escalation within the same kernel security domain; it does not by itself cross a VM/host or IOMMU boundary.
- C:HConfidentiality impact, high
- Observing partially published subrequest entries yields stale start/len/flags/io_iter values, causing out-of-bounds kernel reads and information disclosure from adjacent memory via mis-sized iterators.
- I:HIntegrity impact, high
- Corrupted subrequest metadata drives wrong-span reissue_read/write, erroneous list deletion, and refcount manipulation, providing heap corruption primitives that can be leveraged for arbitrary kernel writes and code execution.
- A:HAvailability impact, high
- Incorrect list traversal and mis-issued I/O can cause use-after-free, refcount underflow, kernel oops, or panic, reliably crashing or hanging the affected system.