The vulnerability lies in the RSA and DSA public key parsers of golang.org/x/crypto/ssh, which lack size restrictions on key parameters. A malicious public key containing an exceedingly large modulus or DSA parameter can trigger several minutes of intense CPU usage during signature verification. This results in a denial‑of‑service condition for the SSH service without requiring any prior authentication.

This flaw affects the golang.org/x/crypto/ssh library. Versions released before the fix do not enforce maximum key lengths for RSA and DSA, while recent releases enforce a maximum RSA modulus of 8192 bits and validate DSA parameters in accordance with FIPS 186‑2.

The CVSS score for this issue is not provided in the data, and no EPSS value is available, indicating that the likelihood of exploitation cannot be quantified here. The vulnerability is not listed in CISA KEV, but it can be triggered by any unauthenticated client attempting public‑key authentication. An attacker can craft a specially sized key to consume compute resources and potentially degrade service availability.