ipv6: Fix null-ptr-deref in fib6_nh_mtu_change().
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
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
- Added to Heist Feed
- Publisher date