ipv6: Fix null-ptr-deref in fib6_nh_mtu_change().
Summary
| CVE | CVE-2026-64538 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-27 21:17:06 UTC |
| Updated | 2026-07-27 21:17:06 UTC |
| Description | 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 |
Risk And Classification
EPSS: 0.001760000 probability, percentile 0.074350000 (date 2026-07-29)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected c0b220cf7d80eb8a36ae9f12cae6df4577a6814e d08d019f2f43a6f9a71e81868bbc326b3afaf37b git | Not specified |
| CNA | Linux | Linux | affected c0b220cf7d80eb8a36ae9f12cae6df4577a6814e 1451deca9896957159f0666520a792c1b861af4f git | Not specified |
| CNA | Linux | Linux | affected c0b220cf7d80eb8a36ae9f12cae6df4577a6814e b2c70dd3326809429b709a9c7e9220d29923051a git | Not specified |
| CNA | Linux | Linux | affected c0b220cf7d80eb8a36ae9f12cae6df4577a6814e 302d57ed7872838b40e56a868fb4c7da7da606e9 git | Not specified |
| CNA | Linux | Linux | affected c0b220cf7d80eb8a36ae9f12cae6df4577a6814e 80600b5d0f3ecb9324120dc95b5e915130f516c5 git | Not specified |
| CNA | Linux | Linux | affected c0b220cf7d80eb8a36ae9f12cae6df4577a6814e b0d0eb13a0441a8ebf4f227843deaf494f1e2c33 git | Not specified |
| CNA | Linux | Linux | affected c0b220cf7d80eb8a36ae9f12cae6df4577a6814e 6428634f7a0b7878144b4925c37856bef3224967 git | Not specified |
| CNA | Linux | Linux | affected c0b220cf7d80eb8a36ae9f12cae6df4577a6814e 46c3b8191aad3d032776bf3bebf03efdf5f4b905 git | Not specified |
| CNA | Linux | Linux | affected 5.3 | Not specified |
| CNA | Linux | Linux | unaffected 5.3 semver | Not specified |
| CNA | Linux | Linux | unaffected 5.10.261 5.10.* semver | Not specified |
| CNA | Linux | Linux | unaffected 5.15.212 5.15.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.178 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.145 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.97 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.40 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1.5 7.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2-rc1 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/80600b5d0f3ecb9324120dc95b5e915130f516c5 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/b2c70dd3326809429b709a9c7e9220d29923051a | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/1451deca9896957159f0666520a792c1b861af4f | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/46c3b8191aad3d032776bf3bebf03efdf5f4b905 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/b0d0eb13a0441a8ebf4f227843deaf494f1e2c33 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/6428634f7a0b7878144b4925c37856bef3224967 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/302d57ed7872838b40e56a868fb4c7da7da606e9 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/d08d019f2f43a6f9a71e81868bbc326b3afaf37b | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.