CVE-2025-15467
Issue summary: Parsing CMS AuthEnvelopedData or EnvelopedData message with maliciously crafted AEAD parameters can trigger a stack buffer overflow.
Impact summary: A stack buffer overflow may lead to a crash, causing Denial of Service, or potentially remote code execution.
When parsing CMS (Auth)EnvelopedData structures that use AEAD ciphers such as AES-GCM, the IV (Initialization Vector) encoded in the ASN.1 parameters is copied into a fixed-size stack buffer without verifying that its length fits the destination. An attacker can supply a crafted CMS message with an oversized IV, causing a stack-based out-of-bounds write before any authentication or tag verification occurs.
Applications and services that parse untrusted CMS or PKCS#7 content using AEAD ciphers (e.g., S/MIME (Auth)EnvelopedData with AES-GCM) are vulnerable. Because the overflow occurs prior to authentication, no valid key material is required to trigger it. While exploitability to remote code execution depends on platform and toolchain mitigations, the stack-based write primitive represents a severe risk.
The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the CMS implementation is outside the OpenSSL FIPS module boundary.
OpenSSL 3.6, 3.5, 3.4, 3.3 and 3.0 are vulnerable to this issue.
OpenSSL 1.1.1 and 1.0.2 are not affected by this issue.
| Software | From | Fixed in |
|---|---|---|
| openssl / openssl | 3.0.0 | 3.0.19 |
| openssl / openssl | 3.3.0 | 3.3.6 |
| openssl / openssl | 3.4.0 | 3.4.4 |
| openssl / openssl | 3.5.0 | 3.5.5 |
| openssl / openssl | 3.6.0 | 3.6.1 |
- http://www.openwall.com/lists/oss-security/2026/01/27/10
- http://www.openwall.com/lists/oss-security/2026/02/25/6
- https://github.com/openssl/openssl/commit/2c8f0e5fa9b6ee5508a0349e4572ddb74db5a703
- https://github.com/openssl/openssl/commit/5f26d4202f5b89664c5c3f3c62086276026ba9a9
- https://github.com/openssl/openssl/commit/6ced0fe6b10faa560e410e3ee8d6c82f06c65ea3
- https://github.com/openssl/openssl/commit/ce39170276daec87f55c39dad1f629b56344429e
- https://github.com/openssl/openssl/commit/d0071a0799f20cc8101730145349ed4487c268dc
- https://openssl-library.org/news/secadv/20260127.txt
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A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
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