Distribution advisory
This page covers CVE-2026-3591 as tracked by Ubuntu, for the package bind9. The fix is available in version 1:9.20.11-1ubuntu2.2; 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 low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity low, availability none.
CVSS metrics in full
The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
- Attack vector: Network — reachable from anywhere that can route to the service.
- Attack complexity: Low — the attack works reliably, with no preparation.
- Privileges required: Low — an ordinary user account is enough.
- User interaction: None — nobody has to be tricked into anything.
- Scope: Unchanged — the damage stays inside the vulnerable component.
- Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
- Integrity impact: Low — limited, and the attacker does not choose what is affected.
- Availability impact: None.
Weakness class
UBUNTU-CVE-2026-3591 is classified as CWE-305: Authentication Bypass by Primary Weakness. The authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error.
Affected software
UBUNTU-CVE-2026-3591 is recorded against 3 packages.
- bind9 (fixed in 1:9.20.11-1ubuntu2.2)
- bind9-libs
- isc-dhcp
Timeline and source
Published on 25 March 2026 and last revised on 20 May 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)
Other advisories for this package
bind9 has other advisories on record. If you are patching this one, these are worth checking on the same host:
Same weakness in other software
These advisories are the same class of weakness (CWE-305: Authentication Bypass by Primary Weakness) in other software:
