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CVE-2026-81736— Remote CPU denial of service through cached SVCB/HTTPS AliasMode trees

Quick assessment

Affected
ISC BIND 9
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

如果 BIND 解析器已缓存了一组 SVCB/HTTPS 别名模式（AliasMode）记录，随后又对该记录的根节点发起查询时，解析器在构造响应过程中会消耗不成比例的 CPU 时间。 此问题影响以下版本的 BIND 9：9.18.0 至 9.18.50、9.20.0 至 9.20.27、9.21.0 至 9.21.25、9.18.11-S1 至 9.18.50-S1，以及 9.20.9-S1 至 9.20.27-S1。

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service
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I. Basic Information for CVE-2026-81736

Vulnerability Information
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Vulnerability Title
Remote CPU denial of service through cached SVCB/HTTPS AliasMode trees
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
循环内过多的平台资源消耗
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
ISC BIND 9 9.18.0 ~ 9.18.50 -

II. Public POCs for CVE-2026-81736

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III. Intelligence Information for CVE-2026-81736

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Vendor Advisories for CVE-2026-81736 (1)

Vendor Pages for CVE-2026-81736 (2)

Same Patch Batch · ISC · 2026-09-16 · 14 CVEs total

CVE-2026-19667 7.5 HIGH Remote assertion failure via 16-bit length truncation in `dns_ncache_add()`
CVE-2026-77692 7.5 HIGH Unauthenticated remote crash of named via a single DoH SIG(0) request
CVE-2026-81563 7.5 HIGH SVCB AliasMode additional-data error leaks qpcache references
CVE-2026-19666 7.5 HIGH Use-after-free in query_addnoqnameproof() via the DNS64 filter64 path
CVE-2026-80274 7.5 HIGH Validating resolver can abort while caching a mismatched NOQNAME proof
CVE-2026-76163 7.5 HIGH named aborts on a TKEY query when the user configuration has no global options statement
CVE-2026-19033 6.5 MEDIUM Unauthenticated IXFR deltas are applied to the live zone before TSIG verification
CVE-2026-19662 5.9 MEDIUM qpcache NOQNAME proof use-after-free crashes recursive resolver
CVE-2026-19941 5.9 MEDIUM checkwildcard() accepts an out-of-zone NSEC as a wildcard-nonexistence proof
CVE-2026-77119 5.9 MEDIUM NSEC3 insecure-referral proof can use unrelated cached NSEC3 RRsets
CVE-2026-78301 5.8 MEDIUM Out-of-zone database nodes can become authoritative zone cuts
CVE-2026-75029 5.3 MEDIUM Message parser retains every identical singleton RDATA, enabling wire-to-work amplificatio
CVE-2026-19668 5.3 MEDIUM Resource Exhaustion via Excessive DNSSEC Cryptographic Material Matching

IV. Related Vulnerabilities

Same product: BIND 9
Same vendor: ISC
Same weakness: CWE-1050

V. Comments for CVE-2026-81736

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