CVE-2025-39817efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare
- 7.1HighCVSS base score
- 0.17%Exploitation in 30 daysEPSS · top 94% 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: efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare Observed on kernel 6.6 (present on master as well): BUG: KASAN: slab-out-of-bounds in memcmp+0x98/0xd0 Call trace: kasan_check_range+0xe8/0x190 __asan_loadN+0x1c/0x28 memcmp+0x98/0xd0 efivarfs_d_compare+0x68/0xd8 __d_lookup_rcu_op_compare+0x178/0x218 __d_lookup_rcu+0x1f8/0x228 d_alloc_parallel+0x150/0x648 lookup_open.isra.0+0x5f0/0x8d0 open_last_lookups+0x264/0x828 path_openat+0x130/0x3f8 do_filp_open+0x114/0x248 do_sys_openat2+0x340/0x3c0 __arm64_sys_openat+0x120/0x1a0 If dentry->d_name.len < EFI_VARIABLE_GUID_LEN , 'guid' can become negative, leadings to oob. The issue can be triggered by parallel lookups using invalid filename: T1 T2 lookup_open ->lookup simple_lookup d_add // invalid dentry is added to hash list lookup_open d_alloc_parallel __d_lookup_rcu __d_lookup_rcu_op_compare hlist_bl_for_each_entry_rcu // invalid dentry can be retrieved ->d_compare efivarfs_d_compare // oob Fix it by checking 'guid' before cmp.
Timeline
ID reserved
By Linux
- 5 months later
· 5 months later
Published
- 11 months later
· 11 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 |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.1 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H |
| NVDNVD · Modified | 3.1 | High7.1 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.17% · top 94% of all CVEs (13 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: High 7.1.
Affected products
- affected da27a24383b2b10bf6ebd0db29b325548aafecb4 – < 0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6
- affected da27a24383b2b10bf6ebd0db29b325548aafecb4 – < 794399019301944fd6d2e0d7a51b3327e26c410e
- affected da27a24383b2b10bf6ebd0db29b325548aafecb4 – < 568e7761279b99c6daa3002290fd6d8047ddb6d2
- affected da27a24383b2b10bf6ebd0db29b325548aafecb4 – < d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7
- affected da27a24383b2b10bf6ebd0db29b325548aafecb4 – < 925599eba46045930b850a98ae594d2e3028ac40
- affected da27a24383b2b10bf6ebd0db29b325548aafecb4 – < c2925cd6207079c3f4d040d082515db78d63afbf
- affected da27a24383b2b10bf6ebd0db29b325548aafecb4 – < 71581a82f38e5a4d807d71fc1bb59aead80ccf95
- affected da27a24383b2b10bf6ebd0db29b325548aafecb4 – < a6358f8cf64850f3f27857b8ed8c1b08cfc4685c
- affected 688289c4b745c018b3449b4b4c5a2030083c8eaf
- affected 3.8.2 – < 3.9
- affected 3.9
- unaffected < 3.9
- unaffected 5.4.298 – ≤ 5.4.*
- unaffected 5.10.242 – ≤ 5.10.*
- unaffected 5.15.191 – ≤ 5.15.*
- unaffected 6.1.150 – ≤ 6.1.*
- unaffected 6.6.104 – ≤ 6.6.*
- unaffected 6.12.45 – ≤ 6.12.*
- unaffected 6.16.5 – ≤ 6.16.*
- unaffected 6.17 – ≤ *
References
References11
- https://git.kernel.org/stable/c/0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6 (opens in a new tab)
- https://git.kernel.org/stable/c/794399019301944fd6d2e0d7a51b3327e26c410e (opens in a new tab)
- https://git.kernel.org/stable/c/568e7761279b99c6daa3002290fd6d8047ddb6d2 (opens in a new tab)
- https://git.kernel.org/stable/c/d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7 (opens in a new tab)
- https://git.kernel.org/stable/c/925599eba46045930b850a98ae594d2e3028ac40 (opens in a new tab)
- https://git.kernel.org/stable/c/c2925cd6207079c3f4d040d082515db78d63afbf (opens in a new tab)
- https://git.kernel.org/stable/c/71581a82f38e5a4d807d71fc1bb59aead80ccf95 (opens in a new tab)
- https://git.kernel.org/stable/c/a6358f8cf64850f3f27857b8ed8c1b08cfc4685c (opens in a new tab)
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html (opens in a new tab)
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html (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-2025-29597 (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-2025-39817)Record last updated .