phpseclib before 2.0.31 and 3.x before 3.0.7 mishandles RSA PKCS#1 v1.5 signature verification.

Math/PrimeField.php in phpseclib 3.x before 3.0.19 has an infinite loop with composite primefields.

In Math/BinaryField.php in phpseclib 3 before 3.0.34, excessively large degrees can lead to a denial of service.

In phpseclib before 1.0.22, 2.x before 2.0.46, and 3.x before 3.0.33, some characters in Subject Alternative Name fields in TLS certificates are incorrectly allowed to have a special meaning in regular expressions (such as a + wildcard), leading to name confusion in X.509 certificate host verification.

An issue was discovered in phpseclib 1.x before 1.0.23, 2.x before 2.0.47, and 3.x before 3.0.36. An attacker can construct a malformed certificate containing an extremely large prime to cause a denial of service (CPU consumption for an isPrime primality check). NOTE: this issue was introduced when attempting to fix CVE-2023-27560.

An issue was discovered in phpseclib 1.x before 1.0.23, 2.x before 2.0.47, and 3.x before 3.0.36. When processing the ASN.1 object identifier of a certificate, a sub identifier may be provided that leads to a denial of service (CPU consumption for decodeOID).

phpseclib is a PHP secure communications library. Projects using versions 1.0.26 and below, 2.0.0 through 2.0.51, and 3.0.0 through 3.0.49 are vulnerable to a to padding oracle timing attack when using AES in CBC mode. This issue has been fixed in versions 1.0.27, 2.0.52 and 3.0.50.