CVE-2025-40205
btrfs: avoid potential out-of-bounds in btrfs_encode_fh()
At a glance
- Severity
- HIGH 7.8
- EPSS
- EPSS 0.15 % · percentile 4 (2026-10-27)
- State
- PUBLISHED
- Published
- Updated
- Assigner
- Linux
- NVD status
- Deferred
Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: avoid potential out-of-bounds in btrfs_encode_fh() The function btrfs_encode_fh() does not properly account for the three cases it handles. Before writing to the file handle (fh), the function only returns to the user BTRFS_FID_SIZE_NON_CONNECTABLE (5 dwords, 20 bytes) or BTRFS_FID_SIZE_CONNECTABLE (8 dwords, 32 bytes). However, when a parent exists and the root ID of the parent and the inode are different, the function writes BTRFS_FID_SIZE_CONNECTABLE_ROOT (10 dwords, 40 bytes). If *max_len is not large enough, this write goes out of bounds because BTRFS_FID_SIZE_CONNECTABLE_ROOT is greater than BTRFS_FID_SIZE_CONNECTABLE originally returned. This results in an 8-byte out-of-bounds write at fid->parent_root_objectid = parent_root_id. A previous attempt to fix this issue was made but was lost. https://lore.kernel.org/all/4CADAEEC020000780001B32C@vpn.id2.novell.com/ Although this issue does not seem to be easily triggerable, it is a potential memory corruption bug that should be fixed. This patch resolves the issue by ensuring the function returns the appropriate size for all three cases and validates that *max_len is large enough before writing any data.
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | HIGH 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | Linux |
| CVSS 3.1 | HIGH 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | NVD · 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Secondary) |
European references
- ENISA EUVD · EUVD-2025-150369
- GCVE · GCVE-0-2025-40205
CERT-FR advisories
- CERTFR-2026-AVI-0602 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0545 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0453 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0421 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0397 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0371 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0331 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0247 — Multiples vulnérabilités dans le noyau Linux de SUSE · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0227 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0225 — Multiples vulnérabilités dans le noyau Linux de SUSE · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0218 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0209 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0199 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0194 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0169 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0059 — Multiples vulnérabilités dans le noyau Linux de SUSE · cert.ssi.gouv.fr
- CERTFR-2025-AVI-1140 — Multiples vulnérabilités dans le noyau Linux de SUSE · cert.ssi.gouv.fr
- CERTFR-2025-AVI-1136 — Multiples vulnérabilités dans le noyau Linux de Debian LTS · cert.ssi.gouv.fr
- CERTFR-2025-AVI-1133 — Multiples vulnérabilités dans le noyau Linux de SUSE · cert.ssi.gouv.fr
- CERTFR-2025-AVI-1048 — Multiples vulnérabilités dans le noyau Linux de Debian LTS · cert.ssi.gouv.fr
Affected products
| Product | Versions |
|---|---|
| Linux · Linux | affected be6e8dc0ba84029997075a1ec77b4ddb863cbe15 < 60de2f55d2aca53e81b4ef2a67d7cc9e1eb677db ; affected be6e8dc0ba84029997075a1ec77b4ddb863cbe15 < 742b44342204e5dfe3926433823623c1a0c581df ; affected be6e8dc0ba84029997075a1ec77b4ddb863cbe15 < d3a9a8e1275eb9b87f006b5562a287aea3f6885f ; affected be6e8dc0ba84029997075a1ec77b4ddb863cbe15 < d91f6626133698362bba08fbc04bd72c466806d3 ; affected be6e8dc0ba84029997075a1ec77b4ddb863cbe15 < 0276c8582488022f057b4cec21975a5edf079f47 ; affected be6e8dc0ba84029997075a1ec77b4ddb863cbe15 < 361d67276eb8ec6be8f27f4ad6c6090459438fee |
| Linux · Linux | affected 2.6.29 ; unaffected 0 < 2.6.29 ; unaffected 5.4.301 ≤ 5.4.* ; unaffected 5.10.246 ≤ 5.10.* ; unaffected 5.15.195 ≤ 5.15.* ; unaffected 6.1.157 ≤ 6.1.* |
References
- https://git.kernel.org/stable/c/60de2f55d2aca53e81b4ef2a67d7cc9e1eb677db
- https://git.kernel.org/stable/c/742b44342204e5dfe3926433823623c1a0c581df
- https://git.kernel.org/stable/c/d3a9a8e1275eb9b87f006b5562a287aea3f6885f
- https://git.kernel.org/stable/c/d91f6626133698362bba08fbc04bd72c466806d3
- https://git.kernel.org/stable/c/0276c8582488022f057b4cec21975a5edf079f47
- https://git.kernel.org/stable/c/361d67276eb8ec6be8f27f4ad6c6090459438fee
- https://git.kernel.org/stable/c/43143776b0a7604d873d1a6f3e552a00aa930224
- https://git.kernel.org/stable/c/dff4f9ff5d7f289e4545cc936362e01ed3252742
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |