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

> Remote attackers can cause excessive CPU consumption in BIND resolvers by querying cached SVCB/HTTPS AliasMode trees, leading to denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** ALPINE-CVE-2026-81736, AZL-103362, BELL-CVE-2026-81736, DEBIAN-CVE-2026-81736, ECHO-dc53-2f42-37f2, GHSA-hjmx-qf9h-v7mw, MINI-cm9x-xpv4-6mwv, MINI-cqrf-mhv2-pp7j, MINI-jv25-q8jv-p39x, UBUNTU-CVE-2026-81736

## What is CVE-2026-81736?

CVE-2026-81736 is a high-severity denial of service vulnerability in ISC BIND 9, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-1050 (Excessive Platform Resource Consumption within a Loop)

## Which versions are affected by CVE-2026-81736?


## How do I fix CVE-2026-81736?

Apply the vendor's patch.

## Is CVE-2026-81736 being exploited?

There is no known exploitation of CVE-2026-81736 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-81736 and fix it if it is affected.

What it is: CVE-2026-81736 is a high-severity denial of service vulnerability in ISC BIND 9, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-81736 in the wild and no public exploit code.

Affected product: ISC BIND 9. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-81736/ (Markdown: https://insights.sbomify.com/CVE-2026-81736/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-81736
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-81736
- OSV: https://osv.dev/vulnerability/CVE-2026-81736

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-81736/
Summaries are generated and may contain mistakes; the official description above is the record.