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CVE-2026-64068
netfs: Fix missing locking around retry adding new subreqs
Published 2026-07-19 (3 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-2026-64068 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 | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Fix netfs_retry_read_subrequests() and netfs_retry_write_stream() to take the appropriate lock when adding extra subrequests into stream->subrequests.
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
- 2026-07-19 (3 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
- 0.50%, higher than 41.6% 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 | 6.18.50 | d5c9d19b0ff2 |
| 6.10 | 7.0.11 | 393f3f0d7353 |
| 6.10 | 7.1 | cce18c263e96 |
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 bug is in netfs client retry logic reached when CIFS, Ceph, AFS, or fscache-backed NFS processes I/O responses from a remote server; a malicious or MITM server can trigger retries and race the collector via crafted protocol replies.
- AC:LAttack complexity, low
- An attacker controlling the remote server can force NEED_RETRY conditions and time fast completions during subrequest splitting; they control both sides of the race by sending concurrent responses while the client retries.
- PR:NPrivileges required, none
- Exploitation requires no privileges on the victim host; a remote attacker only needs the client to have an active mount and any process to perform normal reads or writes against it.
- UI:NUser interaction, none
- No victim interaction beyond routine filesystem access on an already-mounted share; readahead, writeback, and daemon I/O can trigger the race without deliberate user action.
- S:UScope, unchanged
- Impact is kernel memory corruption and potential privilege escalation within the kernel; it does not cross a VM, container, or IOMMU security boundary.
- C:HConfidentiality impact, high
- Concurrent unsynchronized list manipulation of refcounted subrequest objects can cause use-after-free, enabling arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- List corruption and use-after-free on heap-allocated subrequests can be leveraged for arbitrary kernel writes and control-flow hijacking.
- A:HAvailability impact, high
- The race can corrupt the subrequest list and trigger kernel oops, panic, or use-after-free crashes during normal network filesystem I/O retries.