# CVE-2026-33846: Gnutls: gnutls: denial of service via heap buffer overflow in dtls handshake fragment reassembly

> Remote attackers can cause denial of service or potential code execution via heap buffer overflow in GnuTLS DTLS handshake fragment reassembly.

- **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:** 4 May 2026
- **Updated:** 14 Oct 2026
- **Also known as:** ALPINE-CVE-2026-33846, AZL-86220, BELL-CVE-2026-33846, DEBIAN-CVE-2026-33846, ECHO-b6ab-fa46-b1fc, GHSA-qcj7-gqxf-2cqq, OESA-2026-2331, OESA-2026-2332, UBUNTU-CVE-2026-33846, USN-8284-1

## What is CVE-2026-33846?

CVE-2026-33846 is a high-severity memory corruption vulnerability in Cert Manager support for Red Hat OpenShift release 1.17, published on 4 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A heap buffer overflow vulnerability exists in the DTLS handshake fragment reassembly logic of GnuTLS. The issue arises in merge_handshake_packet() where incoming handshake fragments are matched and merged based solely on handshake type, without validating that the message_length field remains consistent across all fragments of the same logical message. An attacker can exploit this by sending crafted DTLS fragments with conflicting message_length values, causing the implementation to allocate a buffer based on a smaller initial fragment and subsequently write beyond its bounds using larger, inconsistent fragments. Because the merge operation does not enforce proper bounds checking against the allocated buffer size, this results in an out-of-bounds write on the heap. The vulnerability is remotely exploitable without authentication via the DTLS handshake path and can lead to application crashes or potential memory corruption.

Weakness: CWE-130 (Improper Handling of Length Parameter Inconsistency)

## Which versions are affected by CVE-2026-33846?


## How do I fix CVE-2026-33846?

Apply the vendor's patch.

## Is CVE-2026-33846 being exploited?

There is no known exploitation of CVE-2026-33846 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33846 and fix it if it is affected.

What it is: CVE-2026-33846 is a high-severity memory corruption vulnerability in Cert Manager support for Red Hat OpenShift release 1.17, published on 4 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-2026-33846 in the wild and no public exploit code.

Affected product: Cert Manager support for Red Hat OpenShift release 1.17. 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-2026-33846/ (Markdown: https://insights.sbomify.com/CVE-2026-33846/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33846
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33846
- OSV: https://osv.dev/vulnerability/CVE-2026-33846

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-33846/
Summaries are generated and may contain mistakes; the official description above is the record.