Skip to content
Heist/ feed
Critical

ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach() Sashiko AI-review observed: In ip6_err_gen_icmpv6_unreach(), the skb is an outer IPv4 ICMP error packet where its cb contains an IPv4 inet_skb_parm. When skb is cloned into skb2 and passed to icmp6_send(), it uses IP6CB(skb2). IP6CB interprets the IPv4 inet_skb_parm as an inet6_skb_parm. The cipso offset in inet_skb_parm.opt directly overlaps with dsthao in inet6_skb_parm at offset 18. If an attacker sends a forged ICMPv4 error with a CIPSO IP option, dsthao would be a non-zero offset. Inside icmp6_send(), mip6_addr_swap() is called and uses ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO). This would scan the inner, attacker-controlled IPv6 packet starting at that offset, potentially returning a fake TLV without checking if the remaining packet length can hold the full 18-byte struct ipv6_destopt_hao. Could mip6_addr_swap() then perform a 16-byte swap that extends past the end of the packet data into skb_shared_info? Should the cb array also be cleared in ip6_err_gen_icmpv6_unreach() and ip6ip6_err() to prevent this? This patch implements the first suggestion. I am not sure if ip6ip6_err() needs to be changed. A separate patch would be better anyway.

Announced Source revision 1
Original source ↗

CVE-2026-43038

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-2026-43038

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": "ca15a078bd907df5fc1c009477869c5cbde3b753",
        "lessThan": "c438ba010171b70bad22fc18b1d5bdc3627476e8",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
        "lessThan": "0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
        "lessThan": "a4437faf135da293d16fcc4cc607316742bd0ebb",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
        "lessThan": "3d5127d998de617b130aae96b138dba22ac6a8a7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
        "lessThan": "e41953e7d118e2702bcb217879c173d9d1d3cd4e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
        "lessThan": "a2edbb6393972a02114b6003953a5cef3104fada",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
        "lessThan": "1ceeebd5bd6d855b17a5df625109bfe29129d7cf",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca15a078bd907df5fc1c009477869c5cbde3b753",
        "lessThan": "86ab3e55673a7a49a841838776f1ab18d23a67b5",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ipv6/icmp.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "3.13"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "3.13",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.253",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.203",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.168",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.134",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.81",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.22",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19.12",
        "versionType": "semver",
        "lessThanOrEqual": "6.19.*"
      },
      {
        "status": "unaffected",
        "version": "7.0",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ipv6/icmp.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-43038

Source reference: /cveMetadata/cveId

Publisher severity

critical

Source reference: /containers/cna/metrics

Event
#40009 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement