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
Metrics
No CVSS score has been published yet.
Affected software
Source: the vendor's advisory (CNA). NVD analysis pending.
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux | >= c0b220cf7d80eb8a36ae9f12cae6df4577a6814e, < d08d019f2f43a6f9a71e81868bbc326b3afaf37b; >= c0b220cf7d80eb8a36ae9f12cae6df4577a6814e, < 1451deca9896957159f0666520a792c1b861af4f; >= c0b220cf7d80eb8a36ae9f12cae6df4577a6814e, < b2c70dd3326809429b709a9c7e9220d29923051a; >= c0b220cf7d80eb8a36ae9f12cae6df4577a6814e, < 302d57ed7872838b40e56a868fb4c7da7da606e9; >= c0b220cf7d80eb8a36ae9f12cae6df4577a6814e, < 80600b5d0f3ecb9324120dc95b5e915130f516c5; >= c0b220cf7d80eb8a36ae9f12cae6df4577a6814e, < b0d0eb13a0441a8ebf4f227843deaf494f1e2c33; >= c0b220cf7d80eb8a36ae9f12cae6df4577a6814e, < 6428634f7a0b7878144b4925c37856bef3224967; >= c0b220cf7d80eb8a36ae9f12cae6df4577a6814e, < 46c3b8191aad3d032776bf3bebf03efdf5f4b905 |
| Linux | Linux | 5.3 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | >= V3.1.6, < * |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | >= V3.1.7, < * |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | >= V3.1.6, < * |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | >= V3.1.7, < * |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | >= V3.1.6, < * |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | >= V3.1.7, < * |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | >= V3.1.6, < * |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | >= V3.1.7, < * |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | >= V3.1.6, < * |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | >= V3.1.7, < * |
References
- https://git.kernel.org/stable/c/1451deca9896957159f0666520a792c1b861af4f
- https://git.kernel.org/stable/c/302d57ed7872838b40e56a868fb4c7da7da606e9
- https://git.kernel.org/stable/c/46c3b8191aad3d032776bf3bebf03efdf5f4b905
- https://git.kernel.org/stable/c/6428634f7a0b7878144b4925c37856bef3224967
- https://git.kernel.org/stable/c/80600b5d0f3ecb9324120dc95b5e915130f516c5
- https://git.kernel.org/stable/c/b0d0eb13a0441a8ebf4f227843deaf494f1e2c33
- https://git.kernel.org/stable/c/b2c70dd3326809429b709a9c7e9220d29923051a
- https://git.kernel.org/stable/c/d08d019f2f43a6f9a71e81868bbc326b3afaf37b
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
Timeline
- Published
- Jul 27, 2026
- Last modified
- Nov 10, 2026
- NVD status
- Undergoing Analysis