strparser: make sure __strp_recv isn't running before tearing down the parser
Only espintcp, the strparser user the advisory names, can be affected, in Linux kernel 5.6.0 up to the fixed releases 6.6.160, 6.12.113, 6.18.57 and 7.2.11.
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 6.6.160, 6.12.113, 6.18.57, 7.2.11
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: strparser: make sure __strp_recv isn't running before tearing down the parser The comment above strp_done() claims that if strp is stopped, strp_recv will no longer be called. That's only true if the caller has a mechanism (eg locking) to guarantee that strp_recv() calls that started before strp_stop() have completed by the time we call strp_done(). This adds a dummy lock_sock/release_sock pair to guarantee that any in-flight strp_recv() (which runs under either bh_lock_sock or lock_sock, depending if it's called from ->sk_data_ready or strp_work) has completed. Only espintcp can be affected by this race condition, but this patch makes sure no future user of strp can have the bug. This could crash on strp->sk ("general mode" of strp), but this mode has been here for 9 years and has never been used. It'll be gone soon, no point worrying about it. Switch the stopped/paused/etc bits to u8's to avoid races between strp_stop() and strp_pause/unpause(). A reproducer has been published and turns the possible UAF into an exploit [1].
Timeline
- CVE published
- First seen by cve.now
- Record last updated
Affected versions
- Linux Linux
Version range not reported
- Linux Linux
5.6
- KernelLinux
From 5.6.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.113; From 6.13.0 · fixed in 6.18.57; From 6.19.0 · fixed in 7.2.11
References 8
git.kernel.org
- stable/c/b09071e2f8460b35c7d355addad0fc7b31c6904d
- stable/c/933df60a465b1b82ff92dcd6870504da90ba4e9b
- stable/c/61cc5dac60d50dee06cf5c7b7ab246f9c825a715
- stable/c/a18dd388045dc7263d99a07db9de4e0f149ca8f1
- stable/c/9f3e9fe1b155e9b4572054d8d140586bc3512ecf
- stable/c/d2b5f637b9b67a79a50d42614d10653c13b4e449
- stable/c/eaa3a29004c063d7e9d5ea55636f693f67e6db0f
- stable/c/0984ebc631792acf8fff105112ee74a6b8f1efcc
Questions about CVE-2026-99056
What does this mean?
strparser can free memory that is still in use if the parser is torn down while its receive function is still running. The advisory calls this a possible use-after-free.Source: git.kernel.org
Am I affected, and how do I check?
The advisory says only espintcp can be affected, so check whether the kernel uses espintcp. The affected kernel ranges are 5.6.0 up to 6.6.160, 6.7.0 up to 6.12.113, 6.13.0 up to 6.18.57, and 6.19.0 up to 7.2.11; the running version can be checked with uname -r.Source: git.kernel.org
What should I do about it?
Move to a fixed kernel for the branch in use: 6.6.160, 6.12.113, 6.18.57, or 7.2.11.Source: git.kernel.org
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data