ipv6: ndisc: fix NULL deref in accept_untracked_na()
Summary
| CVE | CVE-2026-64542 |
|---|---|
| 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: ndisc: fix NULL deref in accept_untracked_na() accept_untracked_na() re-fetches the inet6_dev with __in6_dev_get(dev) and dereferences idev->cnf.accept_untracked_na without a NULL check, even though its only caller ndisc_recv_na() already fetched and NULL-checked idev for the same device. Both reads of dev->ip6_ptr run in the same RCU read-side critical section, but a concurrent addrconf_ifdown() can clear dev->ip6_ptr between them: lowering the MTU below IPV6_MIN_MTU calls addrconf_ifdown() without the synchronize_net() that orders the unregister path, so the re-fetch returns NULL and oopses: BUG: KASAN: null-ptr-deref in ndisc_recv_na (net/ipv6/ndisc.c:974) Read of size 4 at addr 0000000000000364 Call Trace: <IRQ> ndisc_recv_na (net/ipv6/ndisc.c:974) icmpv6_rcv (net/ipv6/icmp.c:1193) ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:479) ip6_input_finish (net/ipv6/ip6_input.c:534) ip6_input (net/ipv6/ip6_input.c:545) ip6_mc_input (net/ipv6/ip6_input.c:635) ipv6_rcv (net/ipv6/ip6_input.c:351) </IRQ> It is reachable by an unprivileged user via a network namespace. Pass the caller's already validated idev instead of re-fetching it; the idev stays alive for the whole RCU critical section, so it is safe even after dev->ip6_ptr has been cleared. |
Risk And Classification
EPSS: 0.001680000 probability, percentile 0.064080000 (date 2026-07-29)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected aaa5f515b16b6b3e137779ffb4c9558bb58c1e75 62c719203cb521b64fab74da94a81bdde5c18808 git | Not specified |
| CNA | Linux | Linux | affected aaa5f515b16b6b3e137779ffb4c9558bb58c1e75 a6450f7cfae57b382cbaf66a577765c9a88b3c58 git | Not specified |
| CNA | Linux | Linux | affected aaa5f515b16b6b3e137779ffb4c9558bb58c1e75 63d1c23764de2309cedbb779c75188d257a09d9b git | Not specified |
| CNA | Linux | Linux | affected aaa5f515b16b6b3e137779ffb4c9558bb58c1e75 d186e942365acece7c56d39da05dd63bf95b280a git | Not specified |
| CNA | Linux | Linux | affected 6.0 | Not specified |
| CNA | Linux | Linux | unaffected 6.0 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/a6450f7cfae57b382cbaf66a577765c9a88b3c58 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/62c719203cb521b64fab74da94a81bdde5c18808 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/d186e942365acece7c56d39da05dd63bf95b280a | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/63d1c23764de2309cedbb779c75188d257a09d9b | 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.