High · CVSS 7.5CVE-2026-81736

Remote CPU denial of service through cached SVCB/HTTPS AliasMode treesCVE-2026-81736

Answer in brief

CVE-2026-81736 records a High severity (CVSS 7.5) vulnerability in Remote CPU denial of service through cached SVCB/HTTPS AliasMode trees. The current sources do not mark it as known exploited. The current feed maps ISC/BIND 9 (generic), ISC/BIND 9 (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 16, 2026Updated Oct 26, 2026Source checked Oct 31, 2026First seen by HOL Sep 16, 2026Material review Oct 26, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Not reported

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps ISC/BIND 9 (generic), ISC/BIND 9 (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
ISC/BIND 9generic	9.18.0 \|\| 9.20.0 \|\| 9.21.0 \|\| 9.18.11-S1 \|\| 9.20.9-S1	Not reported
ISC/BIND 9generic	>=9.18.0 <=9.18.50 \|\| >=9.20.0 <=9.20.27 \|\| >=9.21.0 <=9.21.25 \|\| >=9.18.11-S1 <=9.18.50-S1 \|\| >=9.20.9-S1 <=9.20.27-S1	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for ISC/BIND 9, ISC/BIND 9.
Review the reported fix. Source-reported solution: Upgrade to the patched release most closely related to your current version of BIND 9: 9.20.29, 9.21.26, or 9.20.29-S1.

Evidence timeline and material changes

Published upstream
Sep 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 26, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 16, 2026

Sources and claim methodology

Upstream source description

If a BIND resolver has cached a tree of SVCB/HTTPS AliasMode records, and is then queried for the root of that tree, the resolver will spend disproportionate CPU time constructing the response. This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.

Quoted source text, attributed separately from HOL analysis.