# CVE-2026-5950

## Summary

- **CVE ID:** CVE-2026-5950
- **Severity:** MEDIUM
- **CVSS Score:** 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
- **CWE:** CWE-606
- **Published:** May 20, 2026
- **Last Modified:** May 20, 2026

## 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.

## Affected Products

- ISC — BIND 9 (9.18.36)
- ISC — BIND 9 (9.20.8)
- ISC — BIND 9 (9.21.7)
- ISC — BIND 9 (9.18.36-S1)
- ISC — BIND 9 (9.20.9-S1)

## References

- [CNA](https://kb.isc.org/docs/cve-2026-5950)
- [CNA](https://downloads.isc.org/isc/bind9/9.18.49)
- [CNA](https://downloads.isc.org/isc/bind9/9.20.23)
- [CNA](https://downloads.isc.org/isc/bind9/9.21.22)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.66%
- **EPSS Percentile:** 49.5

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._