OpenSSL released a security update on January 27, 2026, addressing 12 vulnerabilities across supported branches, including one High-severity issue with potential remote code execution (RCE), one Moderate, and multiple Low-severity flaws. The most serious vulnerability, CVE-2025-15467 (High), is a pre-authentication stack buffer overflow in CMS AuthEnvelopedData parsing when using AEAD ciphers (e.g., AES-GCM); a crafted CMS message with an oversized IV in ASN.1 parameters can trigger a crash and may enable code execution in applications that parse untrusted CMS/PKCS#7 content (notably S/MIME workflows). Both sources emphasize that while DoS is the most likely outcome in many environments, the presence of a stack write primitive makes the issue operationally significant where untrusted CMS is processed.
A second notable issue, CVE-2025-11187 (Moderate), involves a stack overflow during PKCS#12 MAC verification (PBMAC1/PBKDF2-related validation), where attacker-controlled parameters (e.g., key length) can lead to crashes and potentially more severe impact when processing untrusted PKCS#12 files (e.g., certificate import/export, PKI/CA tooling). Affected versions called out include OpenSSL 3.x (with additional low-severity issues spanning older branches such as 1.0.2 and 1.1.1), and patched releases include 3.6.1, 3.5.5, 3.4.4, 3.3.6, and 3.0.19 (with corresponding fixes for older maintained lines). Datadog notes OpenSSL 3.x FIPS modules are not affected by the highlighted CMS and PKCS#12 overflow issues, and both sources point to higher risk in services that ingest these formats from external or user-supplied inputs (e.g., S/MIME gateways, certificate management services).

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3 events from the most recent confirmed update back to the earliest known activity.
Cybersecurity firm Aisle identified 12 previously undetected vulnerabilities in OpenSSL, including CVE-2025-15467 and CVE-2025-11187. One source says some of the flaws may have existed in the codebase since 1998.
OpenSSL released fixes for the 12 vulnerabilities and recommended upgrading to patched versions including 3.6.1, 3.5.5, 3.4.4, 3.3.6, 3.0.19, and premium 1.1.1ze and 1.0.2zn. The project also advised limiting exposure to untrusted CMS and PKCS#12 inputs because exploitability depends on whether applications parse such data.
On January 27, 2026, the OpenSSL project disclosed details for 12 vulnerabilities affecting versions 1.0.2, 1.1.1, and multiple 3.x releases. The advisory highlighted high-severity CVE-2025-15467 in CMS AuthEnvelopedData parsing, moderate-severity CVE-2025-11187 in PKCS#12 PBMAC1 validation, and 10 low-severity issues.
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