# CVE-2026-12617: Record ordering based unexpected exit with CNAME or DNAME

> A remote attacker can cause the BIND DNS resolver to crash by sending specific CNAME or DNAME query responses, resulting in a 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:** 22 Jul 2026
- **Updated:** 22 Jul 2026
- **Also known as:** ALPINE-CVE-2026-12617, AZL-93138, BELL-CVE-2026-12617, DEBIAN-CVE-2026-12617, ECHO-6d4b-e3ee-0962, GHSA-cc7q-gqfw-hrm4, MINI-39rc-x62r-75jr, MINI-mxv3-2pvf-wcx2, UBUNTU-CVE-2026-12617

## What is CVE-2026-12617?

CVE-2026-12617 is a high-severity denial of service vulnerability in ISC BIND 9, published on 22 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The issue is unexpected program termination based on ordering and/or specific content in responses to queries for CNAME or DNAME, and A records. Specifically, if a client queries for a DNAME and A record below the DNAME to the resolver, and the authoritative server responds positively to the A query but delays the DNAME response and later responds negatively, `named` may quit unexpectedly. Or, if a client queries for a CNAME and A record for the same name to the resolver, and the authoritative server responds positively to the A query but delays the CNAME response and later responds with a self-referential CNAME, the same failure may occur.
This issue affects BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2026-12617?


## How do I fix CVE-2026-12617?

Apply the vendor's patch.

## Is CVE-2026-12617 being exploited?

There is no known exploitation of CVE-2026-12617 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-12617 and fix it if it is affected.

What it is: CVE-2026-12617 is a high-severity denial of service vulnerability in ISC BIND 9, published on 22 Jul 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-2026-12617 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-2026-12617/ (Markdown: https://insights.sbomify.com/CVE-2026-12617/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-12617
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-12617
- OSV: https://osv.dev/vulnerability/CVE-2026-12617

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-12617/
Summaries are generated and may contain mistakes; the official description above is the record.