CVE-2026-5950
Description
An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during bad-server handling, enabling a remote unauthenticated attacker to cause severe resource exhaustion by sending queries that trigger specific retry conditions. This issue affects BIND 9 versions 9.18.36 through 9.18.48, 9.20.8 through 9.20.22, 9.21.7 through 9.21.21, 9.18.36-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| debian | bookworm | fixed | 1:9.18.49-1~deb12u1 |
| debian | bullseye | affected | |
| debian | forky | fixed | 1:9.20.23-1 |
| debian | sid | fixed | 1:9.20.23-1 |
| debian | trixie | fixed | 1:9.20.23-1~deb13u1 |
| sles | affected | | |
| windows | affected | |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| isc | bind | {"startIncluding":"9.18.36","endExcluding":"9.18.49"} | 9.18.49 |
References
- https://downloads.isc.org/isc/bind9/9.18.49
- https://downloads.isc.org/isc/bind9/9.20.23
- https://downloads.isc.org/isc/bind9/9.21.22
- https://kb.isc.org/docs/cve-2026-5950
- https://security-tracker.debian.org/tracker/CVE-2026-5950
- https://www.suse.com/security/cve/CVE-2026-5950.html
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-5950
CWEs
CWE-606
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.