NSS up to and including 3.73 is vulnerable to a heap overflow when handling DER-encoded DSA or RSA-PSS signatures. Applications using NSS for handling signatures encoded within CMS, S/MIME, PKCS #7, or PKCS #12 are likely to be impacted. Applications using NSS for certificate validation or other TLS, X.509, OCSP or CRL functionality may be impacted, depending on how they configure NSS.When verifying a DER-encoded signature, NSS decodes the signature into a fixed-size buffer and passes the buffer to the underlying PKCS #11 module. The length of the signature is not correctly checked when processing DSA and RSA-PSS signatures. DSA and RSA-PSS signatures larger than 16384 bits will overflow the buffer in VFYContextStr. The vulnerable code is located within secvfy.c:vfy_CreateContext