CVE-2026-5950 | BDVDB-2026-334087 Detail

ISCBIND 9

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.

Impact#

Severe resource exhaustion.

Weaknesses#

CWE-606 Unchecked Input for Loop Condition

References#

Exploit#

No public exploit known

History#

Version 12026-05-20Record published in the CVE List.

Published

Published: 2026-05-20
Last modified: 2026-05-20

Vendor information

Vendor: ISC
Product: BIND 9

All ISC vulnerabilities

Score

5.3 Medium

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 51.9.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Not classified

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
>= 9.18.36 and <= 9.18.48
Fixed
Not stated
Vulnerable
>= 9.20.8 and <= 9.20.22
Fixed
Not stated
Vulnerable
>= 9.21.7 and <= 9.21.21
Fixed
Not stated
Vulnerable
>= 9.18.36-S1 and <= 9.18.48-S1
Fixed
Not stated
Vulnerable
>= 9.20.9-S1 and <= 9.20.22-S1
Fixed
Not stated

Scoring System

CVSS v4.0

Not available

CVSS v3.1

5.3 Medium

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

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Privileges Required	None
User Interaction	None
Scope	Unchanged
Confidentiality	None
Integrity	None
Availability	Low

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).