# CVE-2026-44518: liboqs: XMSS Buffer Overread Bug


- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 29 May 2026
- **Updated:** 29 May 2026
- **Also known as:** GHSA-wf7v-fhxj-73m2

## What is CVE-2026-44518?

CVE-2026-44518 is a medium-severity vulnerability in open-quantum-safe liboqs, published on 29 May 2026. 

### Official description

liboqs is a C-language cryptographic library that provides implementations of post-quantum cryptography algorithms. Prior to 0.16.0, an out-of-bounds read has been identified in the XMSS and XMSS^MT stateful signature verification code. When the verification function is called with a signature buffer shorter than the expected signature size for the given parameter set, the implementation does not validate the caller-supplied length and proceeds to read past the end of the buffer. The out-of-bounds bytes are consumed only as input to an internal hash computation and are not returned to the caller, so no oracle exists to leak their contents to an attacker. The primary observable effect is a possible crash (denial of service) of the verifying process if the read crosses into an unmapped memory page. This vulnerability is fixed in 0.16.0.

Weakness: CWE-20 (Improper Input Validation), CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-44518?

It affects 1 product.


Products: Openquantumsafe Liboqs.

## How do I fix CVE-2026-44518?

Upgrade to a fixed version.

## Is CVE-2026-44518 being exploited?

There is no known exploitation of CVE-2026-44518 in the wild and no public exploit code.

## Other vulnerabilities in open-quantum-safe liboqs

- [CVE-2024-31510](https://insights.sbomify.com/CVE-2024-31510/): Other in n/a (critical 9.8)
- [CVE-2024-54137](https://insights.sbomify.com/CVE-2024-54137/): liboqs has a correctness error in HQC decapsulation (high 7.4)
- [CVE-2025-52473](https://insights.sbomify.com/CVE-2025-52473/): liboqs secret-dependent branching in HQC reference implementation when compiled with Clang 17-20 (medium 5.9)
- [CVE-2024-36405](https://insights.sbomify.com/CVE-2024-36405/): Information disclosure in liboqs (medium 5.9)
- [CVE-2026-46344](https://insights.sbomify.com/CVE-2026-46344/): liboqs: Heap-buffer-overflow in XMSS verification path via OID-controlled parameter mismatch (xmss_commons.c:194) (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44518 and fix it if it is affected.

What it is: CVE-2026-44518 is a medium-severity vulnerability in open-quantum-safe liboqs, published on 29 May 2026. 
Exploitation: There is no known exploitation of CVE-2026-44518 in the wild and no public exploit code.

Affected product: open-quantum-safe liboqs. 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-2026-44518/ (Markdown: https://insights.sbomify.com/CVE-2026-44518/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44518
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44518
- OSV: https://osv.dev/vulnerability/CVE-2026-44518

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-44518/
Summaries are generated and may contain mistakes; the official description above is the record.