GNU wget is vulnerable to denial of service in its FTP OPIE/S-KEY authentication functionality. The server-supplied sequence number from the FTP challenge line is used as an iteration count for an MD5 key-derivation loop without any upper bound validation. A malicious FTP server or a network attacker positioned to intercept FTP traffic can send a crafted OPIE challenge with a sequence number near INT_MAX, causing wget to perform up to approximately 2.1 billion MD5 computations and suspend for some time. The --timeout option does not mitigate this because it applies only to network I/O, not CPU computation. This issue was fixed in commit e9697d98e7249b0f68a6be040a4f3dcc5bc101fa

wget2 accepts a server certificate with incorrect Key Usage (KU) or Extended Key Usage (EKU). If the attackers compromise a certificate (with the associated private key) issued for a different purpose, they may be able to reuse it for TLS server authentication.

A security issue was discovered in GNU Wget2 when handling Metalink documents. The application fails to properly validate file paths provided in Metalink <file name> elements. An attacker can abuse this behavior to write files to unintended locations on the system. This can lead to data loss or potentially allow further compromise of the user’s environment.

A flaw was found in GNU Wget2. This vulnerability, a stack-based buffer overflow, occurs in the filename sanitization logic when processing attacker-controlled URL paths, particularly when filename restriction options are active. A remote attacker can exploit this by providing a specially crafted URL, which, upon user interaction with wget2, can lead to memory corruption. This can cause the application to crash and potentially allow for further malicious activities.