Distribution advisory
This page covers CVE-2026-11721 as tracked by Ubuntu, for the package bind9. The fix is available in version 1:9.20.24-1ubuntu0.2; 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 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 high, availability none.
CVSS metrics in full
The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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: None — an unauthenticated stranger can try it.
- User interaction: None — nobody has to be tricked into anything.
- Scope: Unchanged — the damage stays inside the vulnerable component.
- Confidentiality impact: None.
- Integrity impact: High — total loss, or loss the attacker controls.
- Availability impact: None.
Weakness class
UBUNTU-CVE-2026-11721 is classified as CWE-1284: Improper Validation of Specified Quantity in Input. The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.
Affected software
UBUNTU-CVE-2026-11721 is recorded against 3 packages.
- bind9 (fixed in 1:9.20.24-1ubuntu0.2)
- bind9-libs
- isc-dhcp
Timeline and source
Published on 22 July 2026 and last revised on 19 August 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-1284: Improper Validation of Specified Quantity in Input) in other software:
