CVE-2026-64538
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
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| Linux Linux |
≥ c0b220cf7d80eb8a36ae9f12cae6df4577a6814e; < d08d019f2f43a6f9a71e81868bbc326b3afaf37b (affected, git) ≥ c0b220cf7d80eb8a36ae9f12cae6df4577a6814e; < 1451deca9896957159f0666520a792c1b861af4f (affected, git) ≥ c0b220cf7d80eb8a36ae9f12cae6df4577a6814e; < b2c70dd3326809429b709a9c7e9220d29923051a (affected, git) ≥ c0b220cf7d80eb8a36ae9f12cae6df4577a6814e; < 302d57ed7872838b40e56a868fb4c7da7da606e9 (affected, git) ≥ c0b220cf7d80eb8a36ae9f12cae6df4577a6814e; < 80600b5d0f3ecb9324120dc95b5e915130f516c5 (affected, git) ≥ c0b220cf7d80eb8a36ae9f12cae6df4577a6814e; < b0d0eb13a0441a8ebf4f227843deaf494f1e2c33 (affected, git) ≥ c0b220cf7d80eb8a36ae9f12cae6df4577a6814e; < 6428634f7a0b7878144b4925c37856bef3224967 (affected, git) ≥ c0b220cf7d80eb8a36ae9f12cae6df4577a6814e; < 46c3b8191aad3d032776bf3bebf03efdf5f4b905 (affected, git) Other versions: unaffected |
CNA: Linux |
| Linux Linux |
5.3 (affected) ≥ 0; < 5.3 (unaffected, semver) ≥ 5.10.261; ≤ 5.10.* (unaffected, semver) ≥ 5.15.212; ≤ 5.15.* (unaffected, semver) ≥ 6.1.178; ≤ 6.1.* (unaffected, semver) ≥ 6.6.145; ≤ 6.6.* (unaffected, semver) ≥ 6.12.97; ≤ 6.12.* (unaffected, semver) ≥ 6.18.40; ≤ 6.18.* (unaffected, semver) ≥ 7.1.5; ≤ 7.1.* (unaffected, semver) ≥ 7.2; ≤ * (unaffected, original_commit_for_fix) Other versions: affected |
CNA: Linux |
| SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) Siemens |
≥ V3.1.6; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) Siemens |
≥ V3.1.7; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) Siemens |
≥ V3.1.6; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) Siemens |
≥ V3.1.7; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) Siemens |
≥ V3.1.6; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) Siemens |
≥ V3.1.7; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) Siemens |
≥ V3.1.6; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) Siemens |
≥ V3.1.7; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) Siemens |
≥ V3.1.6; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
| SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) Siemens |
≥ V3.1.7; < * (affected, custom)
Other versions: unknown |
ADP: siemens-SADP |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
No CVSS assessment reported. An unscored record is not a low-severity determination.
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://git.kernel.org/stable/c/d08d019f2f43a6f9a71e81868bbc326b3afaf37bCNA: Linux
- https://git.kernel.org/stable/c/1451deca9896957159f0666520a792c1b861af4fCNA: Linux
- https://git.kernel.org/stable/c/b2c70dd3326809429b709a9c7e9220d29923051aCNA: Linux
- https://git.kernel.org/stable/c/302d57ed7872838b40e56a868fb4c7da7da606e9CNA: Linux
- https://git.kernel.org/stable/c/80600b5d0f3ecb9324120dc95b5e915130f516c5CNA: Linux
- https://git.kernel.org/stable/c/b0d0eb13a0441a8ebf4f227843deaf494f1e2c33CNA: Linux
- https://git.kernel.org/stable/c/6428634f7a0b7878144b4925c37856bef3224967CNA: Linux
- https://git.kernel.org/stable/c/46c3b8191aad3d032776bf3bebf03efdf5f4b905CNA: Linux
- https://cert-portal.siemens.com/productcert/html/ssa-019113.htmlADP: siemens-SADP
- https://cert-portal.siemens.com/productcert/html/ssa-457936.htmlADP: siemens-SADP
- https://git.kernel.org/stable/c/1451deca9896957159f0666520a792c1b861af4f416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/302d57ed7872838b40e56a868fb4c7da7da606e9416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/46c3b8191aad3d032776bf3bebf03efdf5f4b905416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/6428634f7a0b7878144b4925c37856bef3224967416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/80600b5d0f3ecb9324120dc95b5e915130f516c5416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/b0d0eb13a0441a8ebf4f227843deaf494f1e2c33416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/b2c70dd3326809429b709a9c7e9220d29923051a416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://git.kernel.org/stable/c/d08d019f2f43a6f9a71e81868bbc326b3afaf37b416baaa9-dc9f-4396-8d5f-8c081fb06d67
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
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