# CVE-2026-72392: ipv6: fib6: fix NULL deref in fib6_walk_continue() on multi-batch dump

Status: published. Published: 2026-08-15. Updated: 2026-11-06.

In the Linux kernel, the following vulnerability has been resolved:

ipv6: fib6: fix NULL deref in fib6_walk_continue() on multi-batch dump

inet6_dump_fib() saves its progress in cb->args[1] as a positional
index within the current hash chain.  Between batches, a concurrent
fib6_new_table() can insert a new table at the chain head, shifting
all existing entries.  The saved index then lands on a different
table, causing fib6_dump_table() to set w->root to the wrong table
while w->node still points into the previous one.
fib6_walk_continue() dereferences w->node->parent (NULL) and panics:

  BUG: kernel NULL pointer dereference, address: 0000000000000008
  RIP: 0010:fib6_walk_continue+0x6e/0x170
  Call Trace:
   <TASK>
   fib6_dump_table.isra.0+0xc5/0x240
   inet6_dump_fib+0xf6/0x420
   rtnl_dumpit+0x30/0xa0
   netlink_dump+0x15b/0x460
   netlink_recvmsg+0x1d6/0x2a0
   ____sys_recvmsg+0x17a/0x190

Fix by storing tb->tb6_id in cb->args[1] instead of a positional
index.  On resume, skip entries until the id matches; a concurrent
head-insert can never match the saved id, so the walker always
resumes on the correct table.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ 1b43af5480c351dbcb2eef478bafe179cbeb6e83; < ee73a32dd258d4af66831ff006b771e19812b322 (affected, git); ≥ 1b43af5480c351dbcb2eef478bafe179cbeb6e83; < 89f9c5fee3c64c5cabc34e65599308fd3c879cf9 (affected, git); ≥ 1b43af5480c351dbcb2eef478bafe179cbeb6e83; < cb90a774a9c6c46961a44949a246fbb61f5f934c (affected, git); ≥ 1b43af5480c351dbcb2eef478bafe179cbeb6e83; < 27210d433a8c5fe6bf7278a04bbaeb49a81d0290 (affected, git); ≥ 1b43af5480c351dbcb2eef478bafe179cbeb6e83; < 059efb48dd746518898faaa9b965511009b59639 (affected, git); ≥ 1b43af5480c351dbcb2eef478bafe179cbeb6e83; < d8a01d27873e04bebd357dc87859aa756e0b28b2 (affected, git); ≥ 1b43af5480c351dbcb2eef478bafe179cbeb6e83; < 110ccbd28c9444866fcc84ba96a2ad64fa6e95ae (affected, git); ≥ 1b43af5480c351dbcb2eef478bafe179cbeb6e83; < 9facb861dc6b9b9ea9793ef5032a9a826f7a4229 (affected, git). Source: CNA: Linux
- Linux / Linux: 2.6.19 (affected); ≥ 0; < 2.6.19 (unaffected, semver); ≥ 5.10.265; ≤ 5.10.* (unaffected, semver); ≥ 5.15.212; ≤ 5.15.* (unaffected, semver); ≥ 6.1.183; ≤ 6.1.* (unaffected, semver); ≥ 6.6.151; ≤ 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). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.22% as of 2026-11-06; percentile 12.17%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/ee73a32dd258d4af66831ff006b771e19812b322 (CNA: Linux)

- https://git.kernel.org/stable/c/89f9c5fee3c64c5cabc34e65599308fd3c879cf9 (CNA: Linux)

- https://git.kernel.org/stable/c/cb90a774a9c6c46961a44949a246fbb61f5f934c (CNA: Linux)

- https://git.kernel.org/stable/c/27210d433a8c5fe6bf7278a04bbaeb49a81d0290 (CNA: Linux)

- https://git.kernel.org/stable/c/059efb48dd746518898faaa9b965511009b59639 (CNA: Linux)

- https://git.kernel.org/stable/c/d8a01d27873e04bebd357dc87859aa756e0b28b2 (CNA: Linux)

- https://git.kernel.org/stable/c/110ccbd28c9444866fcc84ba96a2ad64fa6e95ae (CNA: Linux)

- https://git.kernel.org/stable/c/9facb861dc6b9b9ea9793ef5032a9a826f7a4229 (CNA: Linux)

- https://git.kernel.org/stable/c/059efb48dd746518898faaa9b965511009b59639 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/110ccbd28c9444866fcc84ba96a2ad64fa6e95ae (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/27210d433a8c5fe6bf7278a04bbaeb49a81d0290 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/89f9c5fee3c64c5cabc34e65599308fd3c879cf9 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/9facb861dc6b9b9ea9793ef5032a9a826f7a4229 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/cb90a774a9c6c46961a44949a246fbb61f5f934c (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/d8a01d27873e04bebd357dc87859aa756e0b28b2 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/ee73a32dd258d4af66831ff006b771e19812b322 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-72392; retrieved 2026-11-06; source updated 2026-11-06

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72392; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-72392; retrieved 2026-11-06; source updated Not reported

Revision: 31a64cbcea165700a441473396c81e6e0361bbd5d80d44351ad4d5d80788a16a

Canonical: https://y2.dev/cve/CVE-2026-72392

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