CVE-2026-64419mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()
- 5.5MediumCVSS base score
- 0.12%Exploitation in 30 daysEPSS · top 98% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show() Reading the debugfs "count" file of a memcg-aware shrinker can sleep inside an RCU read-side critical section: BUG: sleeping function called from invalid context at kernel/cgroup/rstat.c:421 RCU nest depth: 1, expected: 0 css_rstat_flush mem_cgroup_flush_stats zswap_shrinker_count shrinker_debugfs_count_show shrinker_debugfs_count_show() invokes the ->count_objects() callback under rcu_read_lock(). The zswap callback flushes memcg stats via css_rstat_flush(), which may sleep, so it must not run under RCU. The RCU lock is not needed here. mem_cgroup_iter() takes RCU internally and returns a memcg holding a css reference (dropped on the next iteration or by mem_cgroup_iter_break()), so the memcg stays alive without it. The shrinker is kept alive by the open debugfs file: shrinker_free() removes the debugfs entries via debugfs_remove_recursive(), which waits for in-flight readers to drain, before call_rcu(..., shrinker_free_rcu_cb). The sibling "scan" handler already invokes the sleeping ->scan_objects() callback with no RCU section. Drop the rcu_read_lock()/rcu_read_unlock().
Timeline
ID reserved
By Linux
- 6 days later
· 6 days later
Published
- 23 days later
· 23 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Analyzed | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.12% · top 98% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.
Affected products
- affected 5035ebc644aec92d55d1bbfe042f35341e4bffb5 – < de5f69b8dae8698ac5e48dfcd30017887cdf4e5a
- affected 5035ebc644aec92d55d1bbfe042f35341e4bffb5 – < e441cbfbd0eaa6404278e985033c33caba4db767
- affected 5035ebc644aec92d55d1bbfe042f35341e4bffb5 – < 2fed79f0fe8c8d28a972c290dbfd693c3546c8c4
- affected 5035ebc644aec92d55d1bbfe042f35341e4bffb5 – < 560e21e8ccff813e84d05f6500907c549a3d6985
- affected 5035ebc644aec92d55d1bbfe042f35341e4bffb5 – < 86237e56091e70f09c0fbf217f9d9c0e08f556c4
- affected 5035ebc644aec92d55d1bbfe042f35341e4bffb5 – < b902890c62d200b3509cb5e09cf1e0a66553c128
- affected 6.0
- unaffected < 6.0
- unaffected 6.1.178 – ≤ 6.1.*
- unaffected 6.6.145 – ≤ 6.6.*
- unaffected 6.12.96 – ≤ 6.12.*
- unaffected 6.18.39 – ≤ 6.18.*
- unaffected 7.1.4 – ≤ 7.1.*
- unaffected 7.2 – ≤ *
References
References6
- https://git.kernel.org/stable/c/de5f69b8dae8698ac5e48dfcd30017887cdf4e5a (opens in a new tab)
- https://git.kernel.org/stable/c/e441cbfbd0eaa6404278e985033c33caba4db767 (opens in a new tab)
- https://git.kernel.org/stable/c/2fed79f0fe8c8d28a972c290dbfd693c3546c8c4 (opens in a new tab)
- https://git.kernel.org/stable/c/560e21e8ccff813e84d05f6500907c549a3d6985 (opens in a new tab)
- https://git.kernel.org/stable/c/86237e56091e70f09c0fbf217f9d9c0e08f556c4 (opens in a new tab)
- https://git.kernel.org/stable/c/b902890c62d200b3509cb5e09cf1e0a66553c128 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-48963 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-64419)Record last updated .