🛡️ CVE-2026-70368 on Debian — stunnel

⚪ Unknown ✅ No Known Exploit OSV

N/A

CVSS Score

0 Low4 Medium7 High9 Critical10

Description

A stack-based out-of-bounds read vulnerability exists in the "s_vlog" function of stunnel, when handling oversized log messages via "vsnprintf". A remote attacker with network access to a stunnel service can send protocol inputs that trigger a log message longer than 1024 bytes, leading to an out-of-bounds stack read and a potential crash. In certain corner cases, the same vulnerability could be used to replace a series of trailing "\n" characters with "\0".

Distribution advisory

This page covers CVE-2026-70368 as tracked by Debian, for the package stunnel. The fix is available in version 3:5.80-1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity low, availability low.

Weakness class

DEBIAN-CVE-2026-70368 is classified as CWE-125: Out-of-bounds Read. The code reads past the limits of a buffer, exposing adjacent memory contents or crashing the process.

Affected software

DEBIAN-CVE-2026-70368 is recorded against 1 package.

stunnel (fixed in 3:5.80-1)

Timeline and source

Published on 4 August 2026 and last revised on 8 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

Details

Severity Unknown

CVSS Score N/A

CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

CWE N/A

Public Exploit ✅ No

Source OSV

Published 2026-08-04

Updated 2026-08-20

Modified 2026-08-08

Fix URL N/A

Affected Packages

Software	From version	Fixed in
stunnel	—	3:5.80-1

References

ADVISORY https://security-tracker.debian.org/tracker/CVE-2026-70368

🔗 NVD 🔗 Mitre

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