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".
| Version | Type | Source | Base | Exp | Imp |
|---|---|---|---|---|---|
| 3.1 | Primary | NVD | 6.5 | 3.9 | 2.5 |
| 3.1 | Primary | cve.org | 6.5 | — | — |
| 3.1 | Secondary | NVD | 6.5 | 3.9 | 2.5 |
| 3.1 | Secondary | ENISA EUVD | 6.5 | — | — |