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

Status: published. Published: 2026-10-26. Updated: 2026-11-04.

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.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/kisli/vmime/pull/363
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/kisli/vmime/commit/e85925eddc638939f0eeb7ee55ec047d04a760d8

## Affected products and versions

- kisli / vmime (kisli/vmime): ≥ 0; ≤ 0.9.2 (affected, custom). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 5.3 (medium); 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; source: CNA: VulnCheck

- CVSS 3.1: 4.3 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N; source: CNA: VulnCheck

- CVSS 4.0: 5.3 (medium); 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 4.3 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.25% as of 2026-11-04; percentile 16.78%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-908

## Exploit evidence

- exploit: https://hackmd.io/@haindpwn/vmime-uuencode-decoder-oob-write (ADP: CISA-ADP)

## References

- https://github.com/kisli/vmime/pull/363 (CNA: VulnCheck; issue-tracking, patch)

- https://github.com/kisli/vmime/commit/e85925eddc638939f0eeb7ee55ec047d04a760d8 (CNA: VulnCheck; patch)

- https://github.com/kisli/vmime (CNA: VulnCheck; product)

- https://github.com/kisli/vmime/blob/v0.9.2/src/vmime/utility/encoder/uuEncoder.cpp#L311 (CNA: VulnCheck; technical-description)

- https://hackmd.io/@haindpwn/vmime-uuencode-decoder-oob-write (CNA: VulnCheck; third-party-advisory)

- https://www.vulncheck.com/advisories/vmime-through-0.9.2-uninitialized-stack-memory-disclosure-via-uuencode-decoder (CNA: VulnCheck; third-party-advisory)

- https://hackmd.io/@haindpwn/vmime-uuencode-decoder-oob-write (ADP: CISA-ADP; exploit)

- https://github.com/kisli/vmime (disclosure@vulncheck.com)

- https://github.com/kisli/vmime/blob/v0.9.2/src/vmime/utility/encoder/uuEncoder.cpp#L311 (disclosure@vulncheck.com)

- https://github.com/kisli/vmime/commit/e85925eddc638939f0eeb7ee55ec047d04a760d8 (disclosure@vulncheck.com)

- https://github.com/kisli/vmime/pull/363 (disclosure@vulncheck.com)

- https://hackmd.io/@haindpwn/vmime-uuencode-decoder-oob-write (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/vmime-through-0.9.2-uninitialized-stack-memory-disclosure-via-uuencode-decoder (disclosure@vulncheck.com)

- https://hackmd.io/@haindpwn/vmime-uuencode-decoder-oob-write (134c704f-9b21-4f2e-91b3-4a467353bcc0)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-116739; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-116739; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-116739; retrieved 2026-11-04; source updated Not reported

Revision: 77779c651892a3ae391b52abd958398afdf8a6084ff7c432da7ffd2d944ceca4

Canonical: https://y2.dev/cve/CVE-2026-116739

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