Loading story…
OpenSSL disclosed CVE-2021-3450, a high-severity certificate-chain validation bypass affecting OpenSSL 1.1.1h through versions preceding 1.1.1k. Applications that explicitly enable X509_V_FLAG_X509_STRICT but fail to set an appropriate certificate-verification purpose can incorrectly accept a non-CA certificate as capable of issuing subordinate certificates. Exploitation requires a narrow certificate-chain configuration, attacker control of a suitable subscriber certificate, and a vulnerable application configuration.
The flaw is categorized as improper certificate validation (CWE-295) and could enable an attacker to undermine certificate-based trust, including impersonation or adversary-in-the-middle activity. Red Hat and NVD rated it CVSS 7.4; organizations using affected OpenSSL 1.1.1 releases should upgrade to OpenSSL 1.1.1k and review applications for strict X.509 validation settings and explicit verification-purpose configuration. OpenSSL 1.0.2 is not affected, while 1.1.0 was unsupported and not analyzed.
See affected versions and whether adversaries are exploiting it.
3 events from the most recent confirmed update back to the earliest known activity.
OpenSSL issued an advisory disclosing high-severity CVE-2021-3450, affecting OpenSSL 1.1.1h and later when applications explicitly enable X509_V_FLAG_X509_STRICT without an appropriate verification purpose. The advisory also disclosed CVE-2021-3449 and recommended affected OpenSSL 1.1.1 users upgrade to version 1.1.1k.
Benjamin Kaduk of Akamai reported CVE-2021-3450 to OpenSSL; Xiang Ding and others at Akamai were credited with its discovery. The issue could bypass checks that prevent non-CA certificates from issuing other certificates under a narrow strict-validation configuration.
Nokia reported CVE-2021-3449 to OpenSSL. The flaw could allow a malicious TLSv1.2 renegotiation ClientHello to crash an affected OpenSSL TLS server through a NULL pointer dereference.
Vulnerabilities, threat actors, malware, products, organizations, and breaches Mallory has linked to this story.
See whether adversaries are exploiting this yet, and where the affected versions run in your environment.
4 references tracked. Mallory keeps watching after this page renders.
cve.org
Open sourceopenssl.org
Open sourceredhat.com
Open sourcecwe.mitre.org
Open sourceMap indicators from this story to your assets and identify affected systems in minutes.
Every observed campaign, victim, and pivot linked to actors named in this story.
Malware, exploits, and IOCs connected to the activity described here.
YARA, Sigma, and Snort rules deployed to your SIEM as soon as they’re published.
Get matching new stories delivered to your team as they break — not the next morning.
Ask questions about this story and take action on the answers.
Other stories Mallory is tracking that overlap on entities, sources, or topic labels.
An **Important** vulnerability tracked as `CVE-2026-33810` affects Go's `crypto/x509` package and can allow a certificate validation bypass during trusted certificate chain verification. The flaw stems from excluded DNS constraints not being correctly applied to wildcard DNS Subject Alternative Names when the SAN's case differs from the constraint, creating a path for a malicious certificate to be accepted when it should be rejected. Red Hat assigned the issue a **CVSS v3 score of 8.8** and warned that affected products could accept malicious certificates from otherwise trusted chains, weakening the certificate trust model. Red Hat said multiple affected products and components have been fixed through security errata, while the CVE record formally tracks the issue as `CVE-2026-33810`.
Aug 20, 2026
A denial-of-service vulnerability tracked as **CVE-2026-32280** was disclosed in Go's standard library, affecting `crypto/x509` and `crypto/tls` during X.509 certificate verification. The flaw stems from excessive certificate chain-building work in `Verify` when an attacker supplies a large number of candidate intermediate certificates, causing uncontrolled CPU and resource consumption and potentially making applications unavailable. The issue affects systems that use Go to process untrusted TLS certificates or X.509 chains, particularly network-facing services that accept attacker-controlled certificate inputs. Red Hat rated the vulnerability **Important** with a **CVSS v3.1 score of 7.5**, mapped it to **CWE-770**, and published fixes across multiple products, including **Red Hat Enterprise Linux 10 golang** and several **Ansible Automation Platform**, **Cryostat**, and **HawtIO** components.
Aug 20, 2026
OpenSSL disclosed a broad set of vulnerabilities affecting ASN.1 parsing, PKCS#12, CMS/PKCS#7, QUIC, OCSP, CMP/CRMF, DH key validation, AEAD cipher handling, and certificate and email validation across the 4.0, 3.6, 3.5, 3.4, and 3.0 branches. The most severe issue, **CVE-2026-45447**, is a high-severity heap use-after-free in `PKCS7_verify()` that can be triggered by specially crafted PKCS#7 or S/MIME signed messages and could lead to crashes, heap corruption, or potentially remote code execution. The advisory also details moderate-severity flaws that could enable forged CMS `AuthEnvelopedData` messages, denial-of-service conditions in QUIC and OCSP processing, a TLS client double-free via OCSP stapling, a QUIC server `NULL` dereference, and cryptographic failures in AES-OCB when applications use the `EVP_Cipher()` one-shot API, alongside numerous lower-severity parsing, validation, and bounds-checking bugs. OpenSSL said most issues were fixed in **4.0.1**, **3.6.3**, **3.5.7**, **3.4.6**, and **3.0.21**, with **1.1.1zh** and **1.0.2zq** issued for supported legacy customers; most flaws were reported as outside the OpenSSL FIPS module boundary, except **CVE-2026-42770**, which affects FIPS modules in multiple supported branches.
Jun 29, 2026