netfilter: nf_conntrack_reasm: guard mac_header adjustment after IPv6 defrag (Linux Linux)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.17 % · percentile 6 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- Linux
- NVD status
- Received
Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_reasm: guard mac_header adjustment after IPv6 defrag nf_ct_frag6_reasm() slides the packet head forward to drop the IPv6 fragment header and then unconditionally advances skb->mac_header: skb->mac_header += sizeof(struct frag_hdr); On the NF_INET_LOCAL_OUT defrag path the skb has no link-layer header yet, so skb->mac_header is still the "not set" sentinel (u16)~0U. Adding sizeof(struct frag_hdr) wraps it to a small value (0xffff + 8 == 7), after which skb_mac_header_was_set() wrongly reports a MAC header is present and skb_mac_header() points into the headroom. The reassembler has done this unconditional add since it was introduced; it was harmless while mac_header was a bare pointer, but wrong once mac_header became a u16 offset whose unset state is the ~0U sentinel tested by skb_mac_header_was_set(). The sibling net/ipv6/reassembly.c does the same relocation and does guard the adjustment; mirror the guard here.
References
- https://git.kernel.org/stable/c/6e8cd710ca35c576f5f2e5a396047c9ac61f75e5
- https://git.kernel.org/stable/c/2a95ec21824a8ad81ad660b12231456fc0ac9830
- https://git.kernel.org/stable/c/bbcdef2061b170af45702ce6b359c02c12acfc94
- https://git.kernel.org/stable/c/cd0d7bbc027b4d3329712cdcdeb4e5567ffd0d58
- https://git.kernel.org/stable/c/53ef70a315420ed31581d38343684b3bf9a3c76d
- https://git.kernel.org/stable/c/a58230f3a7c4f6c3261786bc1efb72c42e68cd25
- https://git.kernel.org/stable/c/00bdce2fda7e430d24cfbc96764a1b96deb31f82
- https://git.kernel.org/stable/c/3b08fed5b7e0d5e3a25d73ef3ba09cd33ade16c9
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-2026-59149
- GCVE · GCVE-0-2026-72250
CERT-FR advisories
- CERTFR-2026-AVI-1432 — Multiples vulnérabilités dans le noyau Linux de SUSE · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1333 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1286 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
Affected products
| Product | Versions |
|---|---|
| Linux · Linux | affected 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 6e8cd710ca35c576f5f2e5a396047c9ac61f75e5 ; affected 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 2a95ec21824a8ad81ad660b12231456fc0ac9830 ; affected 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < bbcdef2061b170af45702ce6b359c02c12acfc94 ; affected 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < cd0d7bbc027b4d3329712cdcdeb4e5567ffd0d58 ; affected 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < 53ef70a315420ed31581d38343684b3bf9a3c76d ; affected 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 < a58230f3a7c4f6c3261786bc1efb72c42e68cd25 |
| Linux · Linux | affected 2.6.15 ; unaffected 0 < 2.6.15 ; unaffected 5.10.261 ≤ 5.10.* ; unaffected 5.15.212 ≤ 5.15.* ; unaffected 6.1.178 ≤ 6.1.* ; unaffected 6.6.145 ≤ 6.6.* |
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 |