CVE-2026-70368

Summary

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 Software

VendorProductVersion RangeStatus

Weaknesses

  • CWE-125: Out-of-bounds Read

Workarounds

To mitigate this issue, avoid exposing stunnel services to untrusted clients. Restrict access to these services to trusted networks only.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: yes
    • Technical Impact: partial

References