CVE-2026-70368 Stunnel: stack-based out-of-bounds read/write in stunnel s_vlog via oversized log message
A remote attacker can cause a crash in stunnel by sending oversized log messages, triggering a stack-based out-of-bounds read.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-70368?
CVE-2026-70368 is a medium-severity memory corruption vulnerability in Mobi-Com Polska Sp. z o.o. Red Hat Enterprise Linux 10, published on 4 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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".
Weakness: CWE-125
Which versions are affected by CVE-2026-70368?
How do I fix CVE-2026-70368?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-70368 being exploited?
There is no known exploitation of CVE-2026-70368 in the wild and no public exploit code.
Sources
Also known as AZL-94574, DEBIAN-CVE-2026-70368, ECHO-3040-3d7b-9a98, GHSA-g6w9-m7h7-wgq9.