High-Severity Vulnerabilities Patched in OpenSSL, WolfSSL

The developers of the OpenSSL and WolfSSL open source cryptographic libraries announced patches for roughly a dozen vulnerabilities each, including high-severity flaws.

Of the 14 vulnerabilities fixed in OpenSSL , one has been assigned a high severity rating. Tracked as CVE-2026-84782, it could allow a remote peer to obtain fragments of heap memory or crash applications that use Datagram TLS (DTLS), a protocol commonly found in VPNs, VoIP and IoT products.

The flaw is triggered during the DTLS handshake, when OpenSSL retransmits a message while sending another one is stalled. This can cause leftover heap data to be sent to the other party in plaintext. If the read reaches unmapped memory, the application crashes, resulting in a denial-of-service (DoS) condition.

The issue has a CVSS score of 8.2 and can be exploited over the network without authentication or user interaction.

The latest OpenSSL releases also fix a medium-severity vulnerability identified as CVE-2026-84783. A remote, unauthenticated peer could exploit the weakness to crash a multi-threaded TLS client and cause a DoS condition.

The remaining security holes have a low severity rating. They mostly lead to DoS conditions, caused by excessive memory or CPU consumption, process crashes, or the termination of DTLS 1.2 connections. The rest could let attackers abuse QUIC servers for DDoS amplification or exploit timing side channels to gather information that could lead to private key recovery.

WolfSSL security patches

WolfSSL developers released version 5.9.4 on September 25. In addition to new features, the latest version patches 11 vulnerabilities, including three classified as high severity.

The high-severity issues can allow attackers to bypass peer authentication in certain WolfSSL configurations.

CVE-2026-93302 exists because WolfSSL ignores the public key when matching a certificate against a trusted peer certificate. A malicious server that knows which CAs a client trusts can present a forged CA clone and bypass authentication. Affected builds include those created for integration with Nginx, HAProxy, Stunnel, Apache httpd, and other applications.

CVE-2026-89102 allows an attacker holding any certificate (and its private key) that chains to a CA trusted by the client to forge certificates for arbitrary identities. CVE-2026-89136 lets a malicious server bypass authentication on clients with Raw Public Key support enabled by selecting an RPK certificate type the client never requested.

Four medium-severity flaws involve certificate validation defects and a handshake sequencing error. They could allow attackers to bypass name constraints, plant an unverified CA in the shared certificate manager, or complete a TLS 1.2 or DTLS 1.2 handshake in place of the legitimate server and send data the client accepts as authentic.

The four low-severity bugs could lead to a use-after-free during connection shutdown, skipped CRL revocation checks, acceptance of certificates with invalid signatures, and server impersonation. Most require specific configurations or legacy API usage.

Related : OpenSSL Silently Fixes ‘HollowByte’ DoS Vulnerability

Related : OpenSSL Patches High-Severity Vulnerability Found With AI

Related : Data Leakage Vulnerability Patched in OpenSSL

Eduard Kovacs (@EduardKovacs) is senior managing editor at SecurityWeek. He worked as a high school IT teacher before starting a career in journalism in 2011. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.

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