OpenSSL Out-of-bounds Write Vulnerability - CVE-2025-68160

Issue summary: Writing large newline-free data into a BIO chain using the line-buffering filter where the next BIO performs short writes can trigger a heap-based out-of-bounds write. Impact summary: This out-of-bounds write can cause memory corruption which typically results in a crash leading to Denial of Service for an application. The line-buffering BIO filter (BIO_f_linebuffer) is not used by default in TLS/SSL data paths. In OpenSSL command-line applications it is typically only pushed onto stdout/stderr on VMS systems. Third-party applications that explicitly use this filter with a BIO chain that can short-write and that write large newline-free data influenced by an attacker would be affected. However the circumstances where this could happen are unlikely to be under attacker control and BIO_f_linebuffer is unlikely to be handling non-curated data controlled by an attacker. For that reason the issue was assessed as Low severity. The FIPS modules in 3.6 3.5 3.4 3.3 and 3.0 are not affected by this issue as the BIO implementation is outside the OpenSSL FIPS module boundary. OpenSSL 3.6 3.5 3.4 3.3 3.0 1.1.1 and 1.0.2 are vulnerable to this issue.