Skip to main content
Live Webinar with SANS (June 25)— Agentic CTI Automation for Fun & ProfitRegister Free
Mallory
High

Missing ASN1_TYPE validation in OpenSSL TS_RESP_verify_response()

IdentifiersCVE-2025-69420CWE-843

CVE-2025-69420 is a type confusion vulnerability in OpenSSL's TimeStamp Response verification path. In TS_RESP_verify_response(), the helper functions ossl_ess_get_signing_cert() and ossl_ess_get_signing_cert_v2() access an ASN1_TYPE union member for the signing certificate attribute without first validating that the ASN.1 type is V_ASN1_SEQUENCE. When a malformed RFC 3161 TimeStamp Response supplies an unexpected ASN1_TYPE, OpenSSL can dereference an invalid or NULL pointer via the ASN1_TYPE union, causing a crash during verification. The issue affects OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0, and 1.1.1. OpenSSL 1.0.2 is not affected. The OpenSSL FIPS modules in 3.5, 3.4, 3.3, and 3.0 are not affected because the vulnerable TimeStamp Response implementation is outside the FIPS module boundary.

Share:
For your environment

Are you exposed to this one?

Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.

ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation causes an application that verifies a malformed TimeStamp Response to crash due to invalid or NULL pointer dereference, resulting in Denial of Service. The provided content states OpenSSL assessed this issue as Low severity and does not believe it can be exploited for data leakage.

Mitigation

If you can’t patch tonight, do this now.

Avoid or restrict processing of untrusted RFC 3161 TimeStamp Response files until patched. If timestamp verification is required, isolate the verification component to limit crash impact, and ensure only trusted or pre-validated timestamp responses are passed to TS_RESP_verify_response(). Systems not using OpenSSL timestamp protocol APIs are not exposed through this code path.

Remediation

Patch, then assume compromise.

Upgrade to a fixed OpenSSL release. The provided content indicates fixes are included in OpenSSL 3.6.1, 3.5.5, 3.4.4, 3.3.6, 3.0.19, and 1.1.1ze. Vendor-packaged products embedding OpenSSL should be updated to the vendor's remediated release as applicable.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
FreebsdFreebsdapplication
OpenSSL Software FoundationOpensslapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity19

Community discussion across Reddit, Mastodon, and other social sources.