# CVE-2026-33845: Gnutls: gnutls: denial of service via dtls zero-length fragment

> Remote attackers can cause denial of service or information disclosure in GnuTLS via malformed DTLS fragments triggering an integer underflow.

- **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:** 30 Apr 2026
- **Updated:** 14 Oct 2026
- **Also known as:** ALPINE-CVE-2026-33845, AZL-85983, BELL-CVE-2026-33845, CLSA-2026-1778172299, CLSA-2026-1778238329, CLSA-2026-1778238907, CLSA-2026-1778239503, CLSA-2026-1778240890, CLSA-2026-1778762233, CLSA-2026-1778774223, CLSA-2026-1779203444, DEBIAN-CVE-2026-33845, ECHO-638c-85ad-8d98, GHSA-cmj5-x3xf-69wq, OESA-2026-2221

## What is CVE-2026-33845?

CVE-2026-33845 is a high-severity vulnerability in Gnu Gnutls, published on 30 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw in GnuTLS DTLS handshake parsing allows malformed fragments with zero length and non-zero offset, leading to an integer underflow during reassembly and resulting in an out-of-bounds read. This issue is remotely exploitable and may cause information disclosure or denial of service.

Weakness: CWE-191 (Integer Underflow (Wrap or Wraparound))

## Which versions are affected by CVE-2026-33845?

It affects 3 products.


Products: Gnu Gnutls, Redhat Enterprise Linux, Redhat Openshift Container Platform.

## How do I fix CVE-2026-33845?

Apply the vendor's patch.

## Is CVE-2026-33845 being exploited?

There is no known exploitation of CVE-2026-33845 in the wild and no public exploit code.

## Other vulnerabilities in Gnu Gnutls

- [CVE-2008-1948](https://insights.sbomify.com/CVE-2008-1948/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-5334](https://insights.sbomify.com/CVE-2017-5334/): Use after free in n/a (critical 9.8)
- [CVE-2017-5336](https://insights.sbomify.com/CVE-2017-5336/): Memory corruption in n/a (critical 9.8)
- [CVE-2017-5337](https://insights.sbomify.com/CVE-2017-5337/): Memory corruption in n/a (critical 9.8)
- [CVE-2008-1949](https://insights.sbomify.com/CVE-2008-1949/): Null dereference in n/a (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33845 and fix it if it is affected.

What it is: CVE-2026-33845 is a high-severity vulnerability in Gnu Gnutls, published on 30 Apr 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-2026-33845 in the wild and no public exploit code.

Affected product: Gnu Gnutls. 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-2026-33845/ (Markdown: https://insights.sbomify.com/CVE-2026-33845/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33845
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33845
- OSV: https://osv.dev/vulnerability/CVE-2026-33845

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33845/
Summaries are generated and may contain mistakes; the official description above is the record.