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. OpenSSL 3.6 users should upgrade to OpenSSL 3.6.1. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.5. OpenSSL 3.4 users should upgrade to OpenSSL 3.4.4. OpenSSL 3.3 users should upgrade to OpenSSL 3.3.6. OpenSSL 3.0 users should upgrade to OpenSSL 3.0.19. OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1ze (premium support customers only). OpenSSL 1.0.2 users should upgrade to OpenSSL 1.0.2zn (premium support customers only).
"The line-buffering BIO filter (BIO_f_linebuffer) is not used by default in TLS/SSL data paths" So JBCS/JWS are not affected.
This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2026:1472 https://access.redhat.com/errata/RHSA-2026:1472
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2026:1473 https://access.redhat.com/errata/RHSA-2026:1473