Vulnerability in Isc Bind
CVE-2026-5950
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.
EPSS: 0.007 (49.2th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
Affected products
- Isc Bind
- Isc Bind 9 — versions 9.18.36, 9.20.8, 9.21.7
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-officer@isc.org (Patch, patch)
- security-officer@isc.org (Patch, patch)
- security-officer@isc.org (Patch, patch)
- security-officer@isc.org (vendor-advisory, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-5950?
- CVE-2026-5950 is a medium-severity vulnerability in Isc Bind, classified under CWE-606. CVSS score: 5.3/10. Published 2026-05-20.
- How severe is CVE-2026-5950?
- Medium severity. CVSS v3 base score is 5.3 out of 10.
- Is CVE-2026-5950 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.