OpenSSL has published security updates addressing a broad collection of flaws across supported branches of its cryptographic library. The issues range from an out-of-bounds heap write during CMS decryption to remotely triggered crashes and memory-exhaustion conditions in CMP, DTLS and QUIC implementations.

Affected branches include OpenSSL 4.0, 3.6, 3.5, 3.4 and 3.0, with certain bugs also reaching premium-supported legacy versions. Although the project rates the leading issues Moderate rather than Critical, the library’s deep presence in servers, appliances and applications makes accurate inventory and coordinated patching essential.

Crafted CMS data can corrupt heap memory

CVE-2026-63072 is an out-of-bounds write in Cryptographic Message Syntax key unwrapping. During decryption, OpenSSL asks how much output space an operation requires. The AES-WRAP-PAD primitive can write and cleanse eight bytes beyond the size reported by that query, creating a mismatch between the allocated buffer and the operation that follows.

An attacker can modify a legitimate encrypted message’s key-wrap algorithm identifier and trigger the condition when an application calls CMS_decrypt(). The resulting write has a fixed size and value. OpenSSL’s assessment points to heap corruption and denial of service as the realistic consequences rather than arbitrary code execution, but a remote crash can still be disruptive in services that process untrusted CMS messages.

CVE-2026-63076, also rated Moderate, affects Certificate Management Protocol handling. During password-based MAC verification, OpenSSL confirms that an algorithm parameter exists but fails to validate its actual type. A crafted request can cause an invalid pointer dereference, allowing an unauthenticated party to crash a CMP server that accepts PBM-protected messages. A client can likewise be affected when it connects to a malicious or intercepted CMP endpoint.

Resource exhaustion spans DTLS, QUIC and CMP

Several Low-severity findings target availability. CVE-2026-54874 abuses buffering of DTLS records associated with a future handshake epoch. Small forged inputs can cause a target to reserve much larger read buffers, producing an amplification of memory consumption reported at roughly 1,200 times the incoming traffic.

CVE-2026-63075 concerns metadata retained for ACK-only packets in OpenSSL’s QUIC stack. A peer that deliberately withholds acknowledgments can make memory use grow within a connection. CVE-2026-63074 creates another growth condition in long-lived CMP server contexts, where extra certificates from rejected messages are not properly cleared.

Two other crash paths cover less common configurations. CVE-2026-14457 can dereference a null pointer when Raw Public Keys are configured without a certificate and a peer sends a particular signature-algorithms extension. CVE-2026-63073 mishandles an untrusted sender distinguished name as a format string during CMP response validation, enabling a hostile endpoint to crash a client.

An authentication gap in empty AEAD messages

CVE-2026-75803 affects use of the EVP_Cipher() interface with empty ciphertext under ChaCha20-Poly1305 and AES-OCB. In that edge case, decryption can report success without verifying the authentication tag. An application that treats that result as proof of authenticity could accept a forged empty message.

Risk therefore depends heavily on how an application uses OpenSSL. Many deployments may never expose CMS or CMP processing, enable the affected RPK setup, or accept empty encrypted messages. Conversely, a specialized product that presents one of these interfaces to an untrusted network may face a direct denial-of-service or integrity threat.

Fixed releases and an upgrade plan

Corrected community releases are 4.0.2, 3.6.4, 3.5.8, 3.4.7 and 3.0.22. Premium support customers have separate fixes for 1.1.1 and, where applicable, 1.0.2. The disclosed issues do not cross the FIPS module boundary, but applications using a FIPS provider can still depend on vulnerable code elsewhere in the OpenSSL library and should be evaluated normally.

• Identify OpenSSL embedded in operating systems, containers, appliances, language runtimes and statically linked applications.
• Map exposed features, especially CMS decryption, CMP servers or clients, DTLS endpoints and QUIC services.
• Upgrade to the fixed release supplied by the operating-system or product vendor and restart affected processes.
• Test protocol interoperability and service stability after the update.
• Apply network limits and process supervision where upgrades cannot be completed immediately.

Version checks alone can be misleading because vendors often backport fixes without changing to the upstream version number an administrator expects. Teams should rely on their distributor’s security advisory and package status, then confirm that every consuming process has loaded the updated library. The breadth of this release makes dependency visibility as important as the patches themselves.