CVE-2025-11936
MediumCVSS 5.3Exploitation Probability (EPSS)
Low risk36th percentile - higher than 36% of all known CVEs
Summary
Improper input validation in the TLS 1.3 KeyShareEntry parsing in wolfSSL v5.8.2 on multiple platforms allows a remote unauthenticated attacker to cause a denial-of-service by sending a crafted ClientHello message containing duplicate KeyShareEntry values for the same supported group, leading to excessive CPU and memory consumption during ClientHello processing.
Risk Assessment
An attacker can remotely exhaust server resources and cause unavailability of services using wolfSSL. No authentication is required, so anyone can perform the attack.
Recommendation
Update wolfSSL to a version containing the fix or apply a workaround validating ClientHello. Consider limiting TLS 1.3 connections from unknown sources.
Other vulnerabilities in wolfSSL
See all- CVE-2017-13099High
wolfSSL versions prior to 3.12.2 provide a weak Bleichenbacher oracle when any TLS cipher suite using RSA key exchange is negotiated. An attacker can recover the private key from a vulnerable wolfSSL application.
- CVE-2017-8855High
wolfSSL versions before 3.11.0 do not prevent wc_DhAgree from accepting a malformed DH key.
- CVE-2017-8854High
wolfSSL versions before 3.10.2 have an out-of-bounds memory access issue when loading crafted DH parameters, leading to a buffer overflow triggered by a malformed temporary DH file.
- CVE-2015-6925High
wolfSSL versions (formerly CyaSSL) before 3.6.8 are vulnerable to a denial of service attack that can be triggered by a crafted DTLS cookie in a ClientHello message.
- CVE-2026-89134Critical
A certificate with no dNSName SAN but another SAN type present bypassed the Subject CN dNSName name-constraint check. This incomplete fix from CVE-2026-6731 was introduced in wolfSSL version 5.9.2.
- CVE-2023-3724Critical
CVE-2023-3724 affects TLS 1.3 clients that do not receive a PSK or KSE extension when connecting to a malicious server. In this case, a default predictable buffer is used for the IKM value, which may lead to session key compromise.
- CVE-2017-2800Critical
A specially crafted x509 certificate can cause a single out of bounds byte overwrite in wolfSSL through 3.10.2 resulting in potential certificate validation vulnerabilities, denial of service and possible remote code execution.
- CVE-2026-95208High
An issue in the ConfirmNameConstraints() function (wolfcrypt/src/asn.c) of wolfSSL v5.9.1 and v5.9.2 allows attackers to cause a Denial of Service (DoS) via providing crafted Certificate Authority certificates, leading to valid certificates without SAN to be incorrectly rejected by wolfSSL-based TLS clients.
- CVE-2026-94417Medium
A vulnerability in wolfSSL causes CRL checking to be skipped for certificates without an OCSP URL when both OCSP and CRL revocation checking are enabled. As a result, a certificate revoked by CRL may be accepted, and a missing OCSP responder is treated as a positive response. The issue affects versions up to 5.9.2 and is reachable over TLS 1.0-1.3 and DTLS.
- CVE-2026-93304Low
A (D)TLS 1.2 client can accept a ChangeCipherSpec message before sending its ClientKeyExchange, allowing an attacker to complete the handshake in place of the server and send data the client accepts as authentic. DTLS 1.2 clients are exposed via datagram reads, and TLS 1.2 clients when using wolfSSL_inject() or read ahead.
Original NVD description (English source)
Improper input validation in the TLS 1.3 KeyShareEntry parsing in wolfSSL v5.8.2 on multiple platforms allows a remote unauthenticated attacker to cause a denial-of-service by sending a crafted ClientHello message containing duplicate KeyShareEntry values for the same supported group, leading to excessive CPU and memory consumption during ClientHello processing.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS