CVE-2026-64294mm: do file ownership checks with the proper mount idmap
- 5.5MediumCVSS base score
- 0.16%Exploitation in 30 daysEPSS · top 95% 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: do file ownership checks with the proper mount idmap Ever since idmapped mounts were introduced, inode ownership checks (for side-channel protection) in mincore() and madvise(MADV_PAGEOUT) were done against the nop_mnt_idmap, which completely ignores the file's mount's idmap. This results in odd edgecases like: 1) mount/bind-mount with an idmap userA:userB:1 2) userB runs an owner_or_capable() check on file that is owned by userA on-disk/in-memory, but owned by userB after idmap translation 3) owner_or_capable() mysteriously fails as the correct idmap wasn't supplied In the case of mincore/madvise MADV_PAGEOUT, this is usually benign, because file_permission(file, MAY_WRITE) will probably succeed, as it uses the proper idmap internally, but it does not need to be the case on e.g a 0444 file where even the owner itself doesn't have permissions to write to it. Since this is clearly not trivial to get right, introduce a file_owner_or_capable() that can carry the correct semantics, and switch the various users in mm to it. The issue was found by manual code inspection & an off-list discussion with Jan Kara.
Timeline
ID reserved
By Linux
- 6 days later
· 6 days later
Published
- 3 months later
· 3 months 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 · Modified | 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)
- 0.16% · top 95% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.
Affected products
- affected 9caccd41541a6f7d6279928d9f971f6642c361af – < 7368bec565bac3e536cd43579dbde1e715e6ba61
- affected 9caccd41541a6f7d6279928d9f971f6642c361af – < b2f3d94ea310bea9d36d53e9d9b3f45e86c1d893
- affected 9caccd41541a6f7d6279928d9f971f6642c361af – < 744b23aa430d52f5c8e4dbff7d71496d6643bed2
- affected 9caccd41541a6f7d6279928d9f971f6642c361af – < 8344bdf0629457e532797b42d9d2bbf2a2900bbf
- affected 9caccd41541a6f7d6279928d9f971f6642c361af – < 5c942ad7df75925ee166e7f0fb36892d8dde376b
- affected 9caccd41541a6f7d6279928d9f971f6642c361af – < 04ba248d02d9eaa3d9077b00a6134caa75fa3e90
- affected 9caccd41541a6f7d6279928d9f971f6642c361af – < e187bc02f8fa4226d62814592cf064ee4557c470
- affected 5.12
- unaffected < 5.12
- unaffected 5.15.217 – ≤ 5.15.*
- unaffected 6.1.184 – ≤ 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
References7
- https://git.kernel.org/stable/c/7368bec565bac3e536cd43579dbde1e715e6ba61 (opens in a new tab)
- https://git.kernel.org/stable/c/b2f3d94ea310bea9d36d53e9d9b3f45e86c1d893 (opens in a new tab)
- https://git.kernel.org/stable/c/744b23aa430d52f5c8e4dbff7d71496d6643bed2 (opens in a new tab)
- https://git.kernel.org/stable/c/8344bdf0629457e532797b42d9d2bbf2a2900bbf (opens in a new tab)
- https://git.kernel.org/stable/c/5c942ad7df75925ee166e7f0fb36892d8dde376b (opens in a new tab)
- https://git.kernel.org/stable/c/04ba248d02d9eaa3d9077b00a6134caa75fa3e90 (opens in a new tab)
- https://git.kernel.org/stable/c/e187bc02f8fa4226d62814592cf064ee4557c470 (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-2026-49006 (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-2026-64294)Record last updated .