7.5

CVE-2026-11721: isc bind 9

CVSS: 7.5v3.1HighUndergoing analysis
AliasesALPINE-CVE-2026-11721UBUNTU-CVE-2026-11721DEBIAN-CVE-2026-11721
Published 22-07-2026Last modified 22-07-2026
Open JSON

Vulnerability summary

CVE-2026-11721 is a high (CVSS 7.5) vulnerability in isc bind 9. EPSS estimates a 0.40% chance of exploitation in the next 30 days, higher than 32.2% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.40%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 23 · Related 11
MGASA-2026-0331OPENSUSE-SU-2026:11375-1OPENSUSE-SU-2026:21489-1RHSA-2026:54071RHSA-2026:54509RHSA-2026:54510

Timeline

  1. 22-07-2026
    PublishedVulnerability first disclosed.
  2. 22-07-2026
    Last modifiedVulnerability information updated.

Description

It is possible for an attacker's zone to respond to a query with an RRSIG that has a smaller number of labels than the zone in which the RRSIG is contained. This causes `named` to produce a wildcard name for a zone that is shorter than the attacker's zone, which can result in cache poisoning. For this attack to have any effect, the resolver under attack must have set `synth-from-dnssec yes;` (which is the default). This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

CVSS metrics

5 scores · 5 sources · 1 version

EPSS trend

Probability

0.40%

Chance of exploitation in the next 30 days

Percentile

32%

Versus all other CVEs

30-day change

0.00 pp

From 0.40% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.40%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu3 products
  • bind9All versions (No fix recorded) | < 1:9.9.5.dfsg-3ubuntu0.19+esm15 | < 1:9.10.3.dfsg.P4-8ubuntu1.19+esm11 | < 1:9.11.3+dfsg-1ubuntu1.19+esm6 | < 1:9.18.30-0ubuntu0.20.04.2+esm3 | < 1:9.18.39-0ubuntu0.22.04.5 | < 1:9.18.39-0ubuntu0.24.04.6 | < 1:9.20.24-1ubuntu0.2
  • bind9-libsAll versions (No fix recorded)
  • isc-dhcpAll versions (No fix recorded)
Alpine1 product
  • bind< 9.20.26-r0
Debian1 product
  • bind9< 1:9.18.49-1~deb12u2 | < 1:9.20.26-1~deb13u1 | < 1:9.20.26-1
Isc1 product
  • bind 9≥ 9.11.0, ≤ 9.18.50 | ≥ 9.20.0, ≤ 9.20.24 | ≥ 9.21.0, ≤ 9.21.23 | ≥ 9.11.3-S1, ≤ 9.18.50-S1 | ≥ 9.20.9-S1, ≤ 9.20.24-S1

4 vendors · 6 products

References

10 links