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

CMP Indefinite Cache Growth of ExtraCerts

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 before 1.4.9 fails to validate the memorycost parameter from identity file protection blocks, allowing attackers to trigger out-of-memory conditions during key derivation. Attackers with write access to local identity stores can craft malicious identity files with excessive memorycost values that cause the host to crash when unlocking identities before authentication.

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.

opensslencrypt versions before 1.4.9 fail to authenticate recovery-slot presence in envelope-format encrypted files, allowing attackers to remove recovery slots without re-encrypting the payload. Attackers can modify the file header to delete recovery-slot fields and bypass authentication, silently removing recovery paths the owner deliberately added.

The comparator function used for ordering DTLS packets by sequence numbers did not follow qsort comparator contracts in case of packets with duplicate sequence numbers, which could lead to unstable ordering or undefined behaviour. Return 0 in such cases makes the sorting stable. Additionally, discard packets with same sequence numbers and differing handshake type, so that they don't end up being sorted in the first place.

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.

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 executes untrusted third-party plugins with insufficient controls: the plugin signature policy defaulted to WARN, so an unsigned/unverifiable non-built-in plugin was compiled and executed in the host process at import time, before the runtime sandbox is installed. The only default gate was an incomplete, bypassable AST denylist. If a user is induced to load an attacker's plugin, this results in arbitrary code execution with the privileges of the user running opensslencrypt. Fixed in 1.4.9 by defaulting the signature policy to ENFORCE for non-built-in plugins.

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 fail to sanitize recovery-slot metadata in the desktop GUI, allowing attackers to inject control characters and line separators into the irreversible-removal confirmation dialog. Attackers can craft encrypted files with malicious slot identifiers containing bidi overrides or line-separator characters to forge warning text and deceive users during file removal operations.

opensslencrypt 1.4.x before 1.4.9 contains an optional D-Bus crypto service whose org.freedesktop.DBus.Properties.Set method performs neither a polkit authorization check nor value validation. Any local user on the system bus can call Set without authorization and set MaxConcurrentOperations (to 0/negative, causing the concurrency gate to refuse all subsequent operations, or to a huge value removing the limit) or the unbounded DefaultTimeout, resulting in a persistent denial of service of the root daemon. The D-Bus service exists only on the 1.4.x line and was removed in 1.5.x.

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 before 1.4.9 fails to validate the total field from QR JSON payloads before materializing ranges. Attackers can supply crafted QR images with extremely large total values to trigger unbounded memory allocation and cause denial of service through out-of-memory conditions.

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 contain a shell injection vulnerability in the info command's reconstructed CLI block that interpolates untrusted metadata fields without quoting. Attackers can craft metadata values like peppername containing shell commands that execute when users copy the printed CLI block into a shell.

opensslencrypt versions before 1.4.9 contain a signature verification vulnerability in gpgrunner.verifydetached that accepts revoked and expired keys by only checking VALIDSIG status without inspecting REVKEYSIG, EXPKEYSIG, or gpg exit codes. Attackers holding compromised-then-revoked signing keys or expired project keys can bypass signature verification to execute malicious plugins in the host process.