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ipv6: Fix null-ptr-deref in fib6_nh_mtu_change().

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix null-ptr-deref in fib6_nh_mtu_change(). fib6_nh_mtu_change() re-fetches idev via __in6_dev_get(arg->dev) and dereferences idev->cnf.mtu6 without a NULL check. addrconf_ifdown() clears dev->ip6_ptr with RCU_INIT_POINTER() after rt6_disable_ip() has released tb6_lock, so the RA-driven MTU walk can observe a NULL idev and oops. The caller rt6_mtu_change_route() guards its own __in6_dev_get(), but this re-fetch is unguarded; nexthop-backed routes survive addrconf_ifdown()'s flush, so the walk still reaches it after ip6_ptr is nulled. Return 0 when idev is NULL, matching rt6_mtu_change_route() and the fib6_mtu() fix in commit 5ad509c1fdad ("ipv6: Fix null-ptr-deref in fib6_mtu()."). Oops: general protection fault, ... KASAN: null-ptr-deref in range [0x00000000000002a8-0x00000000000002af] RIP: 0010:fib6_nh_mtu_change+0x203/0x990 rt6_mtu_change_route+0x141/0x1d0 __fib6_clean_all+0xd0/0x160 rt6_mtu_change+0xb4/0x100 ndisc_router_discovery+0x24b5/0x2cb0 icmpv6_rcv+0x12e9/0x1710 ipv6_rcv+0x39b/0x410

Announced Source revision 1
Original source ↗

CVE-2026-64538

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-2026-64538

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": "c0b220cf7d80eb8a36ae9f12cae6df4577a6814e",
        "lessThan": "d08d019f2f43a6f9a71e81868bbc326b3afaf37b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c0b220cf7d80eb8a36ae9f12cae6df4577a6814e",
        "lessThan": "1451deca9896957159f0666520a792c1b861af4f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c0b220cf7d80eb8a36ae9f12cae6df4577a6814e",
        "lessThan": "b2c70dd3326809429b709a9c7e9220d29923051a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c0b220cf7d80eb8a36ae9f12cae6df4577a6814e",
        "lessThan": "302d57ed7872838b40e56a868fb4c7da7da606e9",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c0b220cf7d80eb8a36ae9f12cae6df4577a6814e",
        "lessThan": "80600b5d0f3ecb9324120dc95b5e915130f516c5",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c0b220cf7d80eb8a36ae9f12cae6df4577a6814e",
        "lessThan": "b0d0eb13a0441a8ebf4f227843deaf494f1e2c33",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c0b220cf7d80eb8a36ae9f12cae6df4577a6814e",
        "lessThan": "6428634f7a0b7878144b4925c37856bef3224967",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "c0b220cf7d80eb8a36ae9f12cae6df4577a6814e",
        "lessThan": "46c3b8191aad3d032776bf3bebf03efdf5f4b905",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/ipv6/route.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.3"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.3",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.261",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.212",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.178",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.145",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.97",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.40",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.5",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/ipv6/route.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-64538

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#28466 · Revision 1
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Publisher date
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