Vulnerability · CVE-2026-11622

A DNSSEC validating resolver that is under a random subdomain attack against a DNSSEC-signed zone can suffer from runaway memory usage.

Published Jul 22, 2026 · catalog updated Oct 17, 2026 · Canonical Ubuntu

Check if you run it

No confirmed exploitation is on record for CVE-2026-11622. EPSS is 0.54%. Act only if a listed version of Canonical Ubuntu is installed.

Gaps on this record

No vendor fix or required action is stored. Compare the linked advisory before you change production.

Severity: High7.5
Known exploitation: Not in CISA/VulnCheck KEV
EPSS: 0.54%
Remediation: Advisory link
Affected products: Ubuntu:18.04:LTS isc-dhcp · Ubuntu:20.04:LTS bind9-libs · Ubuntu:22.04:LTS bind9 · Ubuntu:22.04:LTS bind9-libs · Ubuntu:24.04:LTS bind9 · Ubuntu:24.04:LTS isc-dhcp

A DNSSEC validating resolver that is under a random subdomain attack against a DNSSEC-signed zone can suffer from runaway memory usage. The attacker needs to be able to send queries faster than the resolver can perform validation. The increased memory usage can be orders of magnitude beyond the limit configured in the parameter. 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

Ubuntu:18.04:LTS isc-dhcp4.3.5-3ubuntu2, 4.3.5-3ubuntu3, 4.3.5-3ubuntu4
Ubuntu:20.04:LTS bind9-libs1:9.11.16+dfsg-3~build1, 1:9.11.16+dfsg-3~ubuntu1
Ubuntu:22.04:LTS bind90 → 1:9.18.39-0ubuntu0.22.04.5
Ubuntu:22.04:LTS bind9-libs1:9.11.19+dfsg-2.1ubuntu1, 1:9.11.19+dfsg-2.1ubuntu2, 1:9.11.19+dfsg-2.1ubuntu3
Ubuntu:24.04:LTS bind90 → 1:9.18.39-0ubuntu0.24.04.6
Ubuntu:24.04:LTS isc-dhcp4.4.3-P1-2ubuntu5, 4.4.3-P1-4ubuntu1, 4.4.3-P1-4ubuntu2
Ubuntu:26.04:LTS bind90 → 1:9.20.24-1ubuntu0.2
Ubuntu:26.04:LTS isc-dhcp4.4.3-P1-4ubuntu2
Ubuntu:Pro:14.04:LTS bind91:9.9.3.dfsg.P2-4ubuntu1, 1:9.9.3.dfsg.P2-4ubuntu2, 1:9.9.3.dfsg.P2-4ubuntu3
Ubuntu:Pro:16.04:LTS bind91:9.9.5.dfsg-11ubuntu1, 1:9.9.5.dfsg-12, 1:9.9.5.dfsg-12.1
Ubuntu:Pro:18.04:LTS bind91:9.10.3.dfsg.P4-12.6ubuntu1, 1:9.11.2.P1-1ubuntu2, 1:9.11.2.P1-1ubuntu3
Ubuntu:Pro:20.04:LTS bind90 → 1:9.18.30-0ubuntu0.20.04.2+esm3
Ubuntu:Pro:20.04:LTS bind91:9.11.5.P4+dfsg-5.1ubuntu2, 1:9.11.5.P4+dfsg-5.1ubuntu3, 1:9.11.5.P4+dfsg-5.1ubuntu4

How to fix CVE-2026-11622

Recommended remediation
A patch or advisory reference is linked. Open the original publisher for availability by product version.
Official advisories

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-11622. EPSS is 0.54%. Act only if a listed version of Canonical Ubuntu is installed.

Which versions are affected?

Compare what you have installed with 4.3.5-3ubuntu2, 4.3.5-3ubuntu3, 4.3.5-3ubuntu4, 1:9.11.16+dfsg-3~build1, 1:9.11.16+dfsg-3~ubuntu1, 0 → 1:9.18.39-0ubuntu0.22.04.5, 1:9.11.19+dfsg-2.1ubuntu1, 1:9.11.19+dfsg-2.1ubuntu2, 1:9.11.19+dfsg-2.1ubuntu3, 0 → 1:9.18.39-0ubuntu0.24.04.6, 4.4.3-P1-2ubuntu5, 4.4.3-P1-4ubuntu1, 4.4.3-P1-4ubuntu2. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.54%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Ubuntu security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

Aug 26, 2026 · OpenSSF OSV / OSV Scanner
Fix available
bind9 fixed in 1:9.18.39-0ubuntu0.22.04.5; bind9 fixed in 1:9.18.39-0ubuntu0.24.04.6; bind9 fixed in 1:9.20.24-1ubuntu0.2
Aug 26, 2026 · OpenSSF OSV / OSV Scanner
Fix available
bind9 fixed in 1:9.18.39-0ubuntu0.22.04.5
Aug 26, 2026 · OpenSSF OSV / OSV Scanner
Fix available
bind9 fixed in 1:9.18.39-0ubuntu0.24.04.6
Aug 26, 2026 · OpenSSF OSV / OSV Scanner
Fix available
bind9 fixed in 1:9.20.24-1ubuntu0.2
Aug 26, 2026 · OpenSSF OSV / OSV Scanner
Updated
A DNSSEC validating resolver that is under a random subdomain attack against a DNSSEC-signed zone can suffer from runaway memory usage. The attacker needs to be able to send queries faster than the resolver can perform validation. The increased memory usage can be orders of magnitude beyond the limit configured in the parameter. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 thr
Oct 14, 2026 · Ubuntu Security Notices
Detected
Zuyao Xu and Xiang Li discovered that Bind incorrectly handled certain malformed DNSKEY records. A remote attacker could possibly use this issue to cause Bind to consume resources, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, and Ubuntu 18.04 LTS. (CVE-2025-8677) Yuxiao Wu, Yunyi Zhang, Baojun Liu, and Haixin Duan discovered that Bind incorrectly a
Oct 17, 2026 · OpenSSF OSV / OSV Scanner
Fix available
bind9 fixed in 1:9.18.30-0ubuntu0.20.04.2+esm3; bind9 fixed in 1:9.18.39-0ubuntu0.22.04.5; bind9 fixed in 1:9.18.39-0ubuntu0.24.04.6; bind9 fixed in 1:9.20.24-1ubuntu0.2
Oct 17, 2026 · OpenSSF OSV / OSV Scanner
Fix available
bind9 fixed in 1:9.18.30-0ubuntu0.20.04.2+esm3
Oct 17, 2026 · OpenSSF OSV / OSV Scanner
Updated
A DNSSEC validating resolver that is under a random subdomain attack against a DNSSEC-signed zone can suffer from runaway memory usage. The attacker needs to be able to send queries faster than the resolver can perform validation. The increased memory usage can be orders of magnitude beyond the limit configured in the parameter. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 thr

Sources

CVE.orgVulnerability recordCVE-2026-11622
Official CVE identifier
cve.org
FIRST EPSSExploitation probabilityCVE-2026-11622
30-day exploitation probability 0.5%
first.org
OpenSSF OSV / OSV ScannerPackage advisoryUBUNTU-CVE-2026-11622
osv.dev
Ubuntu Security NoticesVendor advisoryCVE-2026-11622
Zuyao Xu and Xiang Li discovered that Bind incorrectly handled certain malformed DNSKEY records. A remote attacker could possibly use this issue to cause Bind to consume resources, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, and
ubuntu.com

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

Priority score

23/100

Evidence confidence: High

A vendor or government advisory agrees with at least one other source.

Confirmed exploitation0/30
EPSS probability1/20
CVSS severity11/15
Public exploit0/10
Internet exposure6/10
Product prevalence5/5
Threat research0/5

Decision signals

Four separate signals — do not infer one from another.

High

CVSS severity
7.5 v3.1
Technical impact. Separate from exploitation likelihood.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS probability
0.54% · p44.34%
Estimated probability of exploitation within 30 days (FIRST).
Known exploitation
No verified KEV listing
Evidence from CISA KEV or VulnCheck KEV only — not from EPSS alone.
Patch availability
Advisory link
A patch or advisory reference is linked. Open the original publisher for availability by product version.

Stacks

Linux Ubuntu Ubuntu 14.04 Ubuntu 16.04 Ubuntu 18.04 Ubuntu 20.04 Ubuntu 22.04 Ubuntu 24.04 Ubuntu 26.04

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