# CVE-2026-3593: Heap use-after-free vulnerability in BIND 9 DNS-over-HTTPS implementation

> Attackers can exploit a use-after-free flaw in BIND 9's DNS-over-HTTPS feature to execute arbitrary code or cause denial of service.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/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:** 20 May 2026
- **Updated:** 1 Sep 2026
- **Also known as:** ALPINE-CVE-2026-3593, AZL-87093, BELL-CVE-2026-3593, DEBIAN-CVE-2026-3593, ECHO-f320-5f3f-a5ac, GHSA-8v2c-7qqj-7wp7, MINI-4mx3-mgfc-c5w8, UBUNTU-CVE-2026-3593, openSUSE-SU-2026:10915-1

## What is CVE-2026-3593?

CVE-2026-3593 is a high-severity use after free vulnerability in Isc Bind, published on 20 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A use-after-free vulnerability exists within the DNS-over-HTTPS implementation.
This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1.
BIND 9 versions 9.18.0 through 9.18.48 and 9.18.11-S1 through 9.18.48-S1 are NOT affected.

Weakness: CWE-825 (Expired Pointer Dereference), CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-3593?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `bind` | openSUSE:Tumbleweed | All versions | 9.20.23-2.1 |

Products: Isc Bind.

## How do I fix CVE-2026-3593?

Apply the vendor's patch.

## Is CVE-2026-3593 being exploited?

There is no known exploitation of CVE-2026-3593 in the wild and no public exploit code.

## Other vulnerabilities in Isc Bind

- [CVE-2008-0122](https://insights.sbomify.com/CVE-2008-0122/): Memory corruption in n/a (critical 10.0)
- [CVE-2001-0010](https://insights.sbomify.com/CVE-2001-0010/): Memory corruption in n/a (critical 10.0)
- [CVE-2001-0011](https://insights.sbomify.com/CVE-2001-0011/): Memory corruption in n/a (critical 10.0)
- [CVE-2001-0013](https://insights.sbomify.com/CVE-2001-0013/): Memory corruption in n/a (critical 10.0)
- [CVE-2000-1029](https://insights.sbomify.com/CVE-2000-1029/): Memory corruption in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3593 and fix it if it is affected.

What it is: CVE-2026-3593 is a high-severity use after free vulnerability in Isc Bind, published on 20 May 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-2026-3593 in the wild and no public exploit code.

Affected product: Isc Bind. 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-2026-3593/ (Markdown: https://insights.sbomify.com/CVE-2026-3593/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3593
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3593
- OSV: https://osv.dev/vulnerability/CVE-2026-3593

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-3593/
Summaries are generated and may contain mistakes; the official description above is the record.