Log in Start free

Vulnerability · Published Aug 4, 2026 · Assigned by redhat

CVE-2026-70368Stunnel: stack-based out-of-bounds read/write in stunnel s_vlog via oversized log message

Medium 6.5

In plain English

A medium-severity out-of-bounds read in stunnel from Mobi-Com Polska Sp. z o.o.. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.4%top 70.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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".

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.24stunnel5.82-r0ALPINE-CVE-2026-70368
Debian:14stunnel3:5.80-1DEBIAN-CVE-2026-70368
Debian:12stunnel4no fix listedDEBIAN-CVE-2026-70368
Debian:13stunnel4no fix listedDEBIAN-CVE-2026-70368

Affected products (as reported)

VendorProductVersions
Mobi-Com Polska Sp. z o.o. stunnel 5.68 – before 5.80
Red Hat Red Hat Enterprise Linux 10 see references
Red Hat Red Hat Enterprise Linux 6 see references
Red Hat Red Hat Enterprise Linux 7 see references
Red Hat Red Hat Enterprise Linux 8 see references
Red Hat Red Hat Enterprise Linux 9 see references

Weakness: CWE-125 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

References