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.
CVE-2026-11721
HIGHPre-NVD 7.57.5—Trending — 3 sources updated this week
EchelonGraph scoreHIGH confidence
Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-07-22. a secondary CVSS source baseline 7.5; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: ghsa, secondary
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: —CVSS: 7.5Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.5
- EG Score
- 7.5(high)
- EG Risk
- 49(Track)EG Risk 49/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity75% × 45%Exploitation0% × 40%Automatability100% × 15%Action: Routine — remediate on your standard cadence. - EPSS
- —
- KEV
- Not listed
Published
July 22, 2026
Last Modified
July 22, 2026
Advisory Details (3)
Auto-updated Jul 22, 2026No patch confirmed yet.
generic
CVE-2026-11721: Cache poisoning possible with label count discrepancy, RRSIG, and wildcards
https://kb.isc.org/docs/cve-2026-11721Vendor Advisories for CVE-2026-11721(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 9× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-23 03:04 UTCEG score recompute
- 2026-07-22 21:59 UTCEG score recompute
- 2026-07-22 21:59 UTCGHSA enrichment
- 2026-07-22 19:05 UTCEG score recompute
- 2026-07-22 19:04 UTCGHSA enrichment
- 2026-07-22 17:09 UTCEG score recompute
- 2026-07-22 17:09 UTCGHSA enrichment
- 2026-07-22 14:48 UTCEG score recompute
- 2026-07-22 14:46 UTCMITRE cvelistV5first tracked
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Same CWE
10 shownCWE-1284
- CVE-2022-20699EG 10.0 KEVEPSS 99%CRITICAL
- CVE-2021-21960EG 10.0CRITICAL
- CVE-2021-21951EG 10.0CRITICAL
- CVE-2021-21950EG 10.0CRITICAL
- CVE-2022-25727EG 9.8CRITICAL
- CVE-2022-36938EG 9.8CRITICAL
- CVE-2022-20385EG 9.8CRITICAL
- CVE-2022-37134EG 9.8EPSS 97%CRITICAL
- CVE-2021-43267EG 9.8EPSS 99%CRITICAL
- CVE-2021-31556EG 9.8CRITICAL
Frequently asked(4)
What is CVE-2026-11721?
CVE-2026-11721 is a high vulnerability published on July 22, 2026. 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…
When was CVE-2026-11721 disclosed?
CVE-2026-11721 was first published in the National Vulnerability Database on July 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
What is the CVSS score of CVE-2026-11721?
CVE-2026-11721 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-11721?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-11721, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-11721
Is Your Infrastructure Affected by CVE-2026-11721?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.