CVE-2026-5950

Name: CVE-2026-5950
Creator: NVD / NIST
Published: 2026-05-20T13:16:40.45+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 0.55%

Last modified Jun 17, 2026

CVE-2026-5950 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. 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 estimates a 0.55% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS Probability

0.55%

41.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-606

Affected Software

Vendor	Product	Versions
Isc	Bind	>= 9.18.36, < 9.18.49
Isc	Bind	>= 9.20.8, < 9.20.23
Isc	Bind	>= 9.21.7, < 9.21.21

References

https://downloads.isc.org/isc/bind9/9.18.49Patch
https://downloads.isc.org/isc/bind9/9.20.23Patch
https://downloads.isc.org/isc/bind9/9.21.22Patch
https://kb.isc.org/docs/cve-2026-5950Vendor Advisory

Timeline

Published: May 20, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-5950?

How severe is CVE-2026-5950?

CVE-2026-5950 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.55% probability of exploitation in the next 30 days.

How do I fix CVE-2026-5950?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-5950?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST