CVE-2026-5950

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

0.7% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-20 13:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-07-23 12:10 UTC Last updatedMost recent change to the record

Details

Published

2026-05-20 13:16 UTC

Last modified

2026-07-23 12:10 UTC

Exploit probability

0.7% · EPSS, next 30 days

Weakness

CWE-606

Record status

Analyzed

Affected

• Isc Bind < 9.18.49
• Isc Bind < 9.20.23
• Isc Bind < 9.21.21

Attack profile CVSS 3.1 · 5.3

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

Low