HIGH · CVSS 3.1 8.8Public PoCEPSS 55.85% (p99)Threat level 65

CVE-2025-15467: CVE-2025-15467: Issue summary: Parsing CMS AuthEnvelopedData or EnvelopedData message with maliciously cra…

openssl · openssl · NVD published 2026-01-27 · posted 2026-01-28 · last modified 2026-10-15

What it is

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.

Weakness	CWE-787 CWE-120
CVSS vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H (source: 134c704f-9b21-4f2e-91b3-4a467353bcc0)
ATT&CK tactics	Initial Access → Execution

Exploitation evidence

First exploit evidence seen: 2026-01-28 (earliest date across the sources below).

Exploited in the wild

No source on this site lists in-the-wild exploitation yet (CISA KEV, VulnCheck KEV).

Public exploit code

GitHub proof-of-concept repositories

5 public repositories from 5 accounts, first seen 2026-01-28. Most starred: guiimoraes/CVE-2025-15467 (15 stars), view repository.

Verify before running: public PoCs can be malicious. Read the code and only run it in an isolated lab. A PoC means exploit code is public, not that this CVE is exploited in the wild.

Sources: nomi-sec/PoC-in-GitHub.

How to fix it

Fixed versions

openssl openssl: upgrade to 3.0.19 or later (affected from 3.0.0)
openssl openssl: upgrade to 3.3.6 or later (affected from 3.1.0)
openssl openssl: upgrade to 3.4.4 or later (affected from 3.4.0)
openssl openssl: upgrade to 3.5.5 or later (affected from 3.5.0)
openssl openssl: upgrade to 3.6.1 or later (affected from 3.6.0)

Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.

Vendor advisories and patches

MITRE ATT&CK mitigations for this chain

M1048 Application Isolation and Sandboxing (for T1190, T1203) : Application isolation will limit what other processes and system features the exploited target can access.
M1037 Filter Network Traffic (for T1190) : Restrict outbound network traffic from public-facing servers to prevent unauthorized connections from initiating communications with attacker-controlled infrastructure. While this may not prevent the initial exploitation, it limits the attacker's ability to verify and control the compromised server post-exploit, reduci
M1030 Network Segmentation (for T1190) : Segment externally facing servers and services from the rest of the network with a DMZ or on separate hosting infrastructure.
M1016 Vulnerability Scanning (for T1190) : Regularly scan externally facing systems for vulnerabilities and establish procedures to rapidly patch systems when critical vulnerabilities are discovered through scanning and through public disclosure.
M1026 Privileged Account Management (for T1190) : Use least privilege for service accounts will limit what permissions the exploited process gets on the rest of the system.
M1050 Exploit Protection (for T1190, T1203) : Web Application Firewalls may be used to limit exposure of applications to prevent exploit traffic from reaching the application.
M1035 Limit Access to Resource Over Network (for T1190) : Ensure that all publicly exposed services are actually intended to be so, and restrict access to any that should only be available internally.
M1051 Update Software (for T1190, T1203) : Update software regularly by employing patch management for externally exposed applications.

Detection Generic guidance

Initial Access: Alert on unusual requests to the affected service (odd paths, oversized payloads, exploit strings) in WAF, reverse-proxy and application logs.
Execution: Watch for the service process spawning shells or script interpreters (cmd.exe, powershell, sh, bash, python) via EDR process-tree rules.

Response checklist Generic guidance

Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.