CVE-2025-69420 Missing ASN1_TYPE validation in TS_RESP_verify_response() function
An attacker can cause a denial of service by providing a malformed TimeStamp Response to applications using OpenSSL's verification function.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-69420?
CVE-2025-69420 is a high-severity vulnerability in Openssl Openssl, published on 27 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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 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.
Weakness: CWE-754
Which versions are affected by CVE-2025-69420?
It affects 1 product.
Products include Openssl Openssl.
How do I fix CVE-2025-69420?
Apply the vendor's patch.
Is CVE-2025-69420 being exploited?
There is no known exploitation of CVE-2025-69420 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in Openssl Openssl
Sources
Also known as ALPINE-CVE-2025-69420, AZL-75269, AZL-75585, AZL-75896, AZL-76122, AZL-76167 and 11 more.