CVE-2025-69420
Published: 27 January 2026
Summary
CVE-2025-69420 is a high-severity Improper Check for Unusual or Exceptional Conditions (CWE-754) vulnerability in Openssl Openssl. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked in the top 46.4% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Requires detection and response to audit logging failures as an unusual or exceptional condition.
Implements detection of unusual or exceptional conditions followed by safe mode entry, reducing the window for exploitation of unchecked conditions.
Training ensures users perform required checks for unusual or exceptional conditions as part of contingency roles, limiting attacker leverage from skipped validations.
IR testing directly validates checks for unusual or exceptional conditions that could indicate security incidents.
Requires ongoing monitoring of organization-defined metrics and analysis, enabling checks for unusual or exceptional conditions.
Security testing routinely checks for unusual or exceptional inputs/conditions, identifying missing validation steps that flaw remediation then resolves.
Requires detection of unusual conditions followed by a controlled transition to the defined failure state.
MTTF determination forces explicit checks for conditions that precede predictable component failure.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Directly enables application crash/DoS via exploitation of the type confusion vulnerability in OpenSSL timestamp verification (T1499.004).
NVD Description
Issue summary: A type confusion vulnerability exists in the TimeStamp Response verification code where an ASN1_TYPE union member is accessed without first validating the type, causing an invalid or NULL pointer dereference when processing a malformed TimeStamp Response file. Impact…
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summary: An application calling TS_RESP_verify_response() with a malformed TimeStamp Response can be caused to dereference an invalid or NULL pointer when reading, resulting in a Denial of Service. The functions ossl_ess_get_signing_cert() and ossl_ess_get_signing_cert_v2() access the signing cert attribute value without validating its type. When the type is not V_ASN1_SEQUENCE, this results in accessing invalid memory through the ASN1_TYPE union, causing a crash. Exploiting this vulnerability requires an attacker to provide a malformed TimeStamp Response to an application that verifies timestamp responses. The TimeStamp protocol (RFC 3161) is not widely used and the impact of the exploit is just a Denial of Service. For these reasons the issue was assessed as Low severity. The FIPS modules in 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the TimeStamp Response implementation is outside the OpenSSL FIPS module boundary. OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0 and 1.1.1 are vulnerable to this issue. OpenSSL 1.0.2 is not affected by this issue.
Deeper analysisAI
CVE-2025-69420 is a type confusion vulnerability in the TimeStamp Response verification code of OpenSSL, where an ASN1_TYPE union member is accessed without first validating the type. This leads to an invalid or NULL pointer dereference when processing a malformed TimeStamp Response file. The issue affects the functions ossl_ess_get_signing_cert() and ossl_ess_get_signing_cert_v2(), which access the signing certificate attribute value without checking if its type is V_ASN1_SEQUENCE, resulting in invalid memory access and a crash. Vulnerable versions include OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0, and 1.1.1; OpenSSL 1.0.2 is not affected, and FIPS modules in versions 3.5, 3.4, 3.3, and 3.0 are outside the affected boundary.
An unauthenticated attacker (PR:N) with network access (AV:N) can exploit this by providing a malformed TimeStamp Response to an application that calls TS_RESP_verify_response() for verification, as defined in RFC 3161. Successful exploitation causes a denial of service through application crash due to the pointer dereference, with no impact on confidentiality or integrity (C:N/I:N/A:H). The CVSS v3.1 base score is 7.5, but the issue was assessed as low severity given the limited use of the TimeStamp protocol and DoS-only impact (CWE-754).
Mitigation involves applying patches from OpenSSL, as detailed in the referenced GitHub commits: 27c7012c91cc986a598d7540f3079dfde2416eb9, 4e254b48ad93cc092be3dd62d97015f33f73133a, 564fd9c73787f25693bf9e75faf7bf6bb1305d4e, 5eb0770ffcf11b785cf374ff3c19196245e54f1b, and a99349ebfc519999edc50620abe24d599b9eb085. Security practitioners should update affected OpenSSL deployments and review applications using TimeStamp Response verification.
Details
- CWE(s)