Heap Use-After-Free in OpenSSL PKCS7verify()
Heap Use-After-Free in OpenSSL PKCS7verify() (CVE-2026-45447) Severity: High
Issue summary: A specially crafted PKCS#7 or S/MIME signed message could trigger a use-after-free during PKCS#7 signature verification.
Impact summary: A use-after-free may result in process crashes, heap corruption, or potentially remote code execution.
When processing a PKCS#7 or S/MIME signed message, if the SignedData digestAlgorithms field is present as an empty ASN.1 SET, OpenSSL may incorrectly free a caller-owned BIO during PKCS7verify(). A subsequent use of the BIO by the calling application results in a use-after-free condition.
In the common case this occurs when the application later calls BIOfree() on the BIO originally passed to PKCS7verify(). Depending on allocator behavior and application-specific BIO usage patterns, this may result in a crash or other memory corruption. In some application contexts this may potentially be exploitable for remote code execution.
Applications that process PKCS#7 or S/MIME signed messages using OpenSSL PKCS#7 APIs may be affected. Applications using the CMS APIs for this processing are not affected.
The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.
OpenSSL 4.0, 3.6, 3.5, 3.4, 3.0, 1.1.1, and 1.0.2 are vulnerable to this issue.
OpenSSL 4.0 users should upgrade to OpenSSL 4.0.1 OpenSSL 3.6 users should upgrade to OpenSSL 3.6.3. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.7. OpenSSL 3.4 users should upgrade to OpenSSL 3.4.6. OpenSSL 3.0 users should upgrade to OpenSSL 3.0.21. OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1zh (premium support customers only). OpenSSL 1.0.2 users should upgrade to OpenSSL 1.0.2zq (premium support customers only).
This issue was reported by Thai Duong (Calif.io in collaboration with Claude and Anthropic Research). on 27th April 2026. The fix was developed by Igor Ustinov.
Excessive Memory Use Buffering DTLS Records for a Future Epoch
Issue summary: When an OpenSSL QUIC server (Listener SSL object) processes valid QUIC Initial packets for unknown destination connection IDs, it can allocate and queue new incoming channels without enforcing any limit.
Issue summary: When OpenSSL processes QUIC traffic from a peer that repeatedly sends ack-eliciting packets while not acknowledging ACK-only responses, the QUIC stack can retain ACK-only packet metadata for the lifetime of the connection.
Heap Buffer Overflow in CMS Key Unwrapping
Issue summary: OpenSSL CMP response validation passed an unexpected response sender distinguished name directly as the format string to ERRraisedata().
Invalid Pointer Dereference in CMP Server via Crafted protectionAlg
A flaw was found in libssh builds using the OpenSSL backend for AES-GCM. In the decrypt path in src/libcrypto.c, the return value from EVPDecryptFinal() was checked incorrectly, so authentication tag verification failures were not handled as integrity failures. This could effectively remove integrity protection for affected AES-GCM sessions and allow an in-path attacker to modify plaintext on the wire without detection.
A double free in the OpenSSL-based TLS certificate revocation checking path of the MongoDB C Driver can be reached by a TLS endpoint that the client already trusts. During the handshake, specially formed certificate data can cause the same heap object to be released twice. An unauthenticated party acting as the trusted endpoint may cause the connecting client application to terminate unexpectedly.
opensslencrypt versions before 1.4.9 contain a weak key derivation vulnerability in the D-Bus CryptoService.EncryptFile handler that uses unstretched SHA-256 instead of Argon2id. Attackers can perform offline password guessing against encrypted files roughly six to seven orders of magnitude faster than documented protection by exploiting the missing key stretching and hash rounds.
opensslencrypt before 1.4.9 fails to re-derive and validate fingerprints when loading identities from identity.json, allowing attackers to substitute public keys in identity stores. Attackers can replace legitimate public keys with their own while maintaining the claimed fingerprint, enabling silent key substitution where encryption uses attacker keys and signature verification appears valid.
opensslencrypt versions before 1.4.9 fail to properly validate key derivation function costs in crafted files, allowing attackers to trigger unbounded memory and CPU exhaustion during pre-authentication processing. Attackers can supply malicious files with excessive KDF parameters to exhaust system resources and crash or wedge the process before password verification occurs.
opensslencrypt versions before 1.4.9 derive the remote-pepper wrap key using unsalted HKDF-SHA256 or bare SHA-256 of the password, allowing identical keys across all users and files. Attackers with access to wrapped pepper blobs can precompute a single dictionary table and perform fleet-wide offline password guessing at hardware speed to recover user passwords.
Heap Use-After-Free in OpenSSL PKCS7verify()
Heap Use-After-Free in OpenSSL PKCS7verify() (CVE-2026-45447) Severity: High
Issue summary: A specially crafted PKCS#7 or S/MIME signed message could trigger a use-after-free during PKCS#7 signature verification.
Impact summary: A use-after-free may result in process crashes, heap corruption, or potentially remote code execution.
When processing a PKCS#7 or S/MIME signed message, if the SignedData digestAlgorithms field is present as an empty ASN.1 SET, OpenSSL may incorrectly free a caller-owned BIO during PKCS7verify(). A subsequent use of the BIO by the calling application results in a use-after-free condition.
In the common case this occurs when the application later calls BIOfree() on the BIO originally passed to PKCS7verify(). Depending on allocator behavior and application-specific BIO usage patterns, this may result in a crash or other memory corruption. In some application contexts this may potentially be exploitable for remote code execution.
Applications that process PKCS#7 or S/MIME signed messages using OpenSSL PKCS#7 APIs may be affected. Applications using the CMS APIs for this processing are not affected.
The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.
OpenSSL 4.0, 3.6, 3.5, 3.4, 3.0, 1.1.1, and 1.0.2 are vulnerable to this issue.
OpenSSL 4.0 users should upgrade to OpenSSL 4.0.1 OpenSSL 3.6 users should upgrade to OpenSSL 3.6.3. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.7. OpenSSL 3.4 users should upgrade to OpenSSL 3.4.6. OpenSSL 3.0 users should upgrade to OpenSSL 3.0.21. OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1zh (premium support customers only). OpenSSL 1.0.2 users should upgrade to OpenSSL 1.0.2zq (premium support customers only).
This issue was reported by Thai Duong (Calif.io in collaboration with Claude and Anthropic Research). on 27th April 2026. The fix was developed by Igor Ustinov.
opensslencrypt before 1.4.9 fails to validate KDF cost parameters in encrypted file metadata and keystore headers, allowing attackers to trigger unbounded memory allocation. Attackers can craft malicious encrypted files declaring arbitrarily large Argon2, scrypt, or balloon KDF parameters to exhaust system memory and crash the process without authentication.
opensslencrypt versions before 1.4.9 store an unkeyed SHA-256 hash of the plaintext in the cleartext file header metadata. Attackers can read this hash without the password to confirm guessed plaintexts offline or fingerprint identical plaintexts across separately-encrypted files.
opensslencrypt versions before 1.4.9 fail to validate server URLs in login and registerwithemail functions, accepting unencrypted http:// URLs and unconfigured hosts. Attackers on the network path can intercept cleartext credentials including clientid, passwords, and JWTs to achieve full keyserver account takeover.
opensslencrypt versions before 1.4.9 fail to sanitize terminal control characters in file metadata printed by the info command. Attackers can craft malicious files containing escape sequences to repaint terminal output and forge verification information displayed to users.
opensslencrypt versions before 1.4.9 fail to escape attacker-controlled keyid values printed to stderr during decrypt auto-detection. Attackers can craft encrypted files with malicious keyid containing escape sequences to repaint terminal output and forge authenticity verification blocks.
Issue summary: ChaCha20-Poly1305 and AES-OCB decryption with an empty ciphertext can report success without verifying the supplied authentication tag when the operation is finalized by calling the EVPCipher() function.
opensslencrypt versions before 1.4.9 use a denylist to identify trusted built-in plugins, allowing unsigned plugins in top-level plugins/ directories and unknown subdirectories to bypass signature verification. Attackers can place malicious unsigned plugins following documented installation paths to achieve arbitrary code execution in the CLI process with access to passwords and cryptographic keys.
opensslencrypt versions before 1.4.9 fail to validate encryption status of embedded post-quantum private keys in file metadata. Attackers can craft files with unencrypted embedded PQC keys that decrypt under any password, bypassing authentication and producing attacker-chosen plaintext with false integrity verification.
opensslencrypt before 1.4.9 fails to prevent namespace collisions between own identities and contacts in IdentityStore, allowing attackers to create shadowed contact entries invisible until the corresponding own identity is deleted. When the own identity is deleted, the shadowed contact becomes visible and resolves to the attacker's keys, enabling silent key substitution for encrypted files.
opensslencrypt versions before 1.4.0 expose passwords passed via the --password CLI argument in process listings accessible to all system users. Attackers can read process arguments through ps aux or /proc/[pid]/cmdline to retrieve plaintext passwords and keystore passwords.
opensslencrypt versions before 1.4.0 use Python's non-cryptographic random module for steganographic pixel selection in the generatepseudorandomsequence function. Attackers who know the password can recover the Mersenne Twister state from approximately 624 outputs and predict pixel locations containing hidden data for extraction.
opensslencrypt versions before 1.4.0 contain a vulnerability in PublicKeyBundle.fromdict() that creates key bundles from untrusted data without verifying signatures. Attackers can call fromdict() followed by toidentity() without signature verification to encrypt data using attacker-controlled public keys, leaking secrets.
opensslencrypt versions before 1.4.0 use an in-memory rate limiter for TOTP brute-force protection that is not shared across workers and is lost on server restart. Attackers can distribute authentication attempts across multiple server instances or retry immediately after a restart to bypass rate limiting protections.
opensslencrypt versions before 1.4.0 accept refresh tokens as URL query parameters in keyserver and telemetry server routes. Attackers can extract tokens from server logs, proxy logs, browser history, and HTTP Referer headers to gain unauthorized access.
opensslencrypt versions before 1.4.0 contain a path traversal vulnerability in the issafepath method where the pluginid parameter is not sanitized before constructing the plugin config directory path. Attackers can declare a malicious pluginid containing path traversal sequences like '../' to access arbitrary directories outside the intended plugin directory.
opensslencrypt versions before 1.4.0 contain a logging bug in restorehiddenmodules() that logs module counts after clearing, always showing zero restored modules and corrupting audit trails. Additionally, a race condition exists between module hiding and import hook installation where another thread could re-import blocked modules in multi-threaded environments.