🛡️ CVE-2026-5950 on Ubuntu — bind9

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

Distribution advisory

This page covers CVE-2026-5950 as tracked by Ubuntu, for the package bind9. The fix is available in version 1:9.20.18-1ubuntu2.1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability low.

Affected software and timeline

Affected software: bind9 (fixed in 1:9.20.18-1ubuntu2.1), bind9-libs and isc-dhcp. Published on 20 May 2026 and last revised on 31 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

ubuntu.com (Report)
www.cve.org (Report)
kb.isc.org (Report)
ubuntu.com (Advisory)

CVE-2026-5950 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-05-20
Updated 2026-08-12
Modified 2026-07-31
Fix URL N/A

Affected Packages

Software From version Fixed in
bind9 — 1:9.20.18-1ubuntu2.1
bind9-libs — —
isc-dhcp — —

Vulnerability Monitoring

Track new vulnerabilities in bind9

UBUNTU-CVE-2026-5950 is rated CVSS 5.3 Medium. BotEraser monitors your WordPress installation and notifies you when software you use appears in our vulnerability database.

Set Up Free Alerts →

No credit card required  ·  Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

More UBUNTU CVE 2026 advisories

Part of UBUNTU CVE 2026 in the advisory index.