CVE-2025-15467 is a critical vulnerability affecting OpenSSL, with a CVSS score of 9.8. This vulnerability allows for a stack buffer overflow when parsing CMS (Auth)EnvelopedData messages containing maliciously crafted AEAD parameters. Attackers can exploit this vulnerability to cause a Denial of Service (DoS) or potentially execute remote code. Given the severity of this vulnerability, it is imperative for organizations to prioritize patching immediately.
The root cause of the vulnerability lies in the way OpenSSL handles the Initialization Vector (IV) during the parsing of CMS structures that utilize AEAD ciphers like AES-GCM. Specifically, the IV is copied into a fixed-size stack buffer without proper length verification. Attackers can exploit this oversight by supplying a crafted CMS message with an oversized IV, leading to an out-of-bounds write before any authentication takes place.
As applications and services parse untrusted CMS or PKCS#7 content using AEAD ciphers, they become vulnerable to this stack buffer overflow. Importantly, the overflow occurs prior to any authentication requirements, meaning that no valid key material is needed to trigger the exploit. While platform and toolchain mitigations may affect the exploitability for remote code execution, the inherent risk associated with this stack-based write primitive is significant.
Organizations utilizing affected versions of OpenSSL, specifically versions 3.0.0 to 3.0.18, 3.3.0 to 3.3.5, 3.4.0 to 3.4.3, and 3.5.0 to 3.5.4, should address this vulnerability as a matter of priority. OpenSSL versions 1.1.1 and 1.0.2 are not affected by this issue. The urgency for remediation is underscored by the vulnerability's potential to disrupt service and enable further exploitation.
Vulnerability Details
The vulnerability CVE-2025-15467 is classified as a critical stack buffer overflow issue affecting OpenSSL, specifically in how it processes CMS AuthEnvelopedData and EnvelopedData messages with malicious AEAD parameters. This vulnerability was first published on January 27, 2026, and is assigned a CVSS score of 9.8, indicating its critical severity level.
The affected versions include OpenSSL 3.0.0 to 3.0.18, 3.3.0 to 3.3.5, 3.4.0 to 3.4.3, and 3.5.0 to 3.5.4. The vulnerability is identified by CWE-787, which pertains to a stack buffer overflow.
Technical Analysis
The vulnerability arises from a failure to verify the length of the IV copied into a fixed-size stack buffer when parsing CMS (Auth)EnvelopedData structures. The attack vector is network-based, requiring no privileges or user interaction, making it relatively easy to exploit from a remote location. The attack complexity is low, and the impacts include high confidentiality, integrity, and availability risks.
Risk & Impact Analysis
Risk to organizations includes service disruption due to Denial of Service (DoS) attacks and the potential for remote code execution. The blast radius extends to any application using vulnerable OpenSSL versions, particularly those handling untrusted CMS content. Organizations should assess their exposure and prioritize remediation efforts based on the critical nature of this vulnerability.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
Affected versions of OpenSSL include 3.0.0 to 3.0.18, 3.3.0 to 3.3.5, 3.4.0 to 3.4.3, and 3.5.0 to 3.5.4. Organizations should ensure they are using patched versions to mitigate this vulnerability.
Mitigation & Remediation
To mitigate this vulnerability, organizations should update to the latest version of OpenSSL that addresses this issue. For detailed guidance on patching and remediation, organizations can refer to the penetration testing services that can validate the effectiveness of the applied fixes.
Detection Guidance
Organizations should monitor log files for signs of exploitation attempts, such as unusual input sizes or malformed CMS messages. Additionally, behavioral anomalies in applications processing CMS data should be tracked to detect potential exploits.
AppSecure Threat Intelligence Insight
This vulnerability highlights a critical oversight in input validation, which is a common point of failure in many security architectures. Security teams should learn from this incident to enhance their security postures against similar vulnerabilities. Regular security assessments and adherence to secure coding practices are essential to safeguard against such risks. For further insights, organizations can explore resources on penetration testing methodology and vulnerability management program design to strengthen defenses.
Moreover, organizations should consider implementing continuous security testing practices, such as those outlined in the continuous security testing guide, to proactively identify and mitigate similar vulnerabilities.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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