# CVE-2026-2646: Heap buffer overflow in session parsing with wolfSSL_d2i_SSL_SESSION() function

> Heap buffer overflow in wolfSSL session parsing allows attackers to corrupt memory and potentially execute code via crafted session data.

- **Severity:** Medium 5.0 (`CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Mar 2026
- **Updated:** 19 Mar 2026
- **Also known as:** DEBIAN-CVE-2026-2646, GHSA-24vq-qfc5-qrmj, JLSEC-2026-702, UBUNTU-CVE-2026-2646

## What is CVE-2026-2646?

CVE-2026-2646 is a medium-severity memory corruption vulnerability in Wolfssl Wolfssl, published on 19 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A heap-buffer-overflow vulnerability exists in wolfSSL's wolfSSL_d2i_SSL_SESSION() function. When deserializing session data with SESSION_CERTS enabled, certificate and session id lengths are read from an untrusted input without bounds validation, allowing an attacker to overflow fixed-size buffers and corrupt heap memory. A maliciously crafted session would need to be loaded from an external source to trigger this vulnerability. Internal sessions were not vulnerable.

Weakness: CWE-787 (Out-of-bounds Write), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-2646?

It affects 1 product.


Products: Wolfssl Wolfssl.

## How do I fix CVE-2026-2646?

Apply the vendor's patch.

## Is CVE-2026-2646 being exploited?

There is no known exploitation of CVE-2026-2646 in the wild and no public exploit code.

## Other vulnerabilities in Wolfssl Wolfssl

- [CVE-2024-5991](https://insights.sbomify.com/CVE-2024-5991/): Buffer overread in domain name matching (critical 10.0)
- [CVE-2021-37155](https://insights.sbomify.com/CVE-2021-37155/): Security feature bypass in n/a (critical 9.8)
- [CVE-2020-36177](https://insights.sbomify.com/CVE-2020-36177/): Memory corruption in n/a (critical 9.8)
- [CVE-2014-2896](https://insights.sbomify.com/CVE-2014-2896/): Memory corruption in n/a (critical 9.8)
- [CVE-2014-2897](https://insights.sbomify.com/CVE-2014-2897/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-2646 and fix it if it is affected.

What it is: CVE-2026-2646 is a medium-severity memory corruption vulnerability in Wolfssl Wolfssl, published on 19 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-2646 in the wild and no public exploit code.

Affected product: Wolfssl Wolfssl. 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-2026-2646/ (Markdown: https://insights.sbomify.com/CVE-2026-2646/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-2646
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-2646
- OSV: https://osv.dev/vulnerability/CVE-2026-2646

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-2646/
Summaries are generated and may contain mistakes; the official description above is the record.