CVE-2026-73252

Name of the Vulnerable Software and Affected Versions Mongoose versions prior to 7.23

Description The built-in TLS stack selected by MG TLS BUILTIN in src/tls builtin.c accepts a TLS 1.3 record where the decrypted size is exactly the 16-byte authentication tag, lacking plaintext or a ContentType byte. Within the mg tls recv record() function, the msgsz length check allows this record, causing the recv len calculation to underflow to SIZE MAX. Consequently, a subsequent handshake step interprets stale buffer contents as a trusted message with an unbounded length. An unauthenticated malicious TLS peer can trigger a heap out-of-bounds read—a condition where the program reads data past the end of the allocated heap memory—before certificate or Finished validation, resulting in a remote denial of service.

Recommendations Update to version 7.23.