Skip to content
Heist/ feed
Critical

ipv6: rpl: reserve mac_len headroom when recompressed SRH grows

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-43501

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-43501

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "bde199c72d319a4e207f88daabc888317504e2fb",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "be1fa0aa9b4fdd5a8b7a61ba520a690a68391e6e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "8e8be63465a5e80394c70324603dfea1bfdad48f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "4babc2d9fda2df43823b85d08a0180b68f1b0854",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "c261d07a80576dc8ccf394ef8f074f8c67a06b37",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "7398ebefbfd4f8a31d4f665a4213302fa995494b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3",
        "lessThan": "9e6bf146b55999a095bb14f73a843942456d1adc",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ipv6/exthdrs.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.7"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.7",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.258",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.209",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.175",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.140",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.86",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.27",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.0.4",
        "versionType": "semver",
        "lessThanOrEqual": "7.0.*"
      },
      {
        "status": "unaffected",
        "version": "7.1",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ipv6/exthdrs.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-43501

Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event
#40085 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement