CVE-2026-43501ipv6: rpl: reserve mac_len headroom when recompressed SRH grows
- 9.8CriticalCVSS base score
- 0.73%Exploitation in 30 daysEPSS · top 45% 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: ipv6: rpl: reserve mac_len headroom when recompressed SRH grows ipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps the next segment into ipv6_hdr->daddr, recompresses, then pulls the old header and pushes the new one plus the IPv6 header back. The recompressed header can be larger than the received one when the swap reduces the common-prefix length the segments share with daddr (CmprI=0, CmprE>0, seg[0][0] != daddr[0] gives the maximum +8 bytes). pskb_expand_head() was gated on segments_left == 0, so on earlier segments the push consumed unchecked headroom. Once skb_push() leaves fewer than skb->mac_len bytes in front of data, skb_mac_header_rebuild()'s call to: skb_set_mac_header(skb, -skb->mac_len); will store (data - head) - mac_len into the u16 mac_header field, which wraps to ~65530, and the following memmove() writes mac_len bytes ~64KiB past skb->head. A single AF_INET6/SOCK_RAW/IPV6_HDRINCL packet over lo with a two segment type-3 SRH (CmprI=0, CmprE=15) reaches headroom 8 after one pass; KASAN reports a 14-byte OOB write in ipv6_rthdr_rcv. Fix this by expanding the head whenever the remaining room is less than the push size plus mac_len, and request that much extra so the rebuilt MAC header fits afterwards.
Timeline
ID reserved
By Linux
- 20 days later
· 20 days later
Published
- 6 months later
· 6 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 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| redhat-SADPADP (enrichment) | 3.1 | High7.5 | CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.73% · top 45% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Affected products
- affected 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 – < bde199c72d319a4e207f88daabc888317504e2fb
- affected 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 – < be1fa0aa9b4fdd5a8b7a61ba520a690a68391e6e
- affected 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 – < 0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402
- affected 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 – < 8e8be63465a5e80394c70324603dfea1bfdad48f
- affected 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 – < 4babc2d9fda2df43823b85d08a0180b68f1b0854
- affected 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 – < c261d07a80576dc8ccf394ef8f074f8c67a06b37
- affected 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 – < 7398ebefbfd4f8a31d4f665a4213302fa995494b
- affected 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 – < 9e6bf146b55999a095bb14f73a843942456d1adc
- affected 5.7
- unaffected < 5.7
- unaffected 5.10.258 – ≤ 5.10.*
- unaffected 5.15.209 – ≤ 5.15.*
- unaffected 6.1.175 – ≤ 6.1.*
- unaffected 6.6.140 – ≤ 6.6.*
- unaffected 6.12.86 – ≤ 6.12.*
- unaffected 6.18.27 – ≤ 6.18.*
- unaffected 7.0.4 – ≤ 7.0.*
- unaffected 7.1 – ≤ *
References
References20
- https://git.kernel.org/stable/c/bde199c72d319a4e207f88daabc888317504e2fb (opens in a new tab)
- https://git.kernel.org/stable/c/be1fa0aa9b4fdd5a8b7a61ba520a690a68391e6e (opens in a new tab)
- https://git.kernel.org/stable/c/0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402 (opens in a new tab)
- https://git.kernel.org/stable/c/8e8be63465a5e80394c70324603dfea1bfdad48f (opens in a new tab)
- https://git.kernel.org/stable/c/4babc2d9fda2df43823b85d08a0180b68f1b0854 (opens in a new tab)
- https://git.kernel.org/stable/c/c261d07a80576dc8ccf394ef8f074f8c67a06b37 (opens in a new tab)
- https://git.kernel.org/stable/c/7398ebefbfd4f8a31d4f665a4213302fa995494b (opens in a new tab)
- https://git.kernel.org/stable/c/9e6bf146b55999a095bb14f73a843942456d1adc (opens in a new tab)
- https://access.redhat.com/security/cve/CVE-2026-43501 (opens in a new tab)vdb-entryx_refsource_REDHAT
- RHBZ#2480457 (opens in a new tab)issue-trackingx_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43501.json (opens in a new tab)x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:27731 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:25191 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:34095 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:27713 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:34094 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:25217 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:33900 (opens in a new tab)vendor-advisoryx_refsource_REDHAT
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-457936.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-2026-31276 (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-2026-43501)Record last updated .