Out-of-bounds Write via an Unbounded RSA Modulus in NetX Secure X.509
- Published
- Last modified
- Status
- published
- Known exploitation
- Not listed in CISA KEV
- Public exploit
- None on Exploit-DB
- Exploitation: none
- Automatable: yes
- Technical impact: total
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Decision points from CISA's Vulnrichment, assessed (SSVC 2.0.3).
SSVC documentationSummary
The X.509 parser in NetX Secure accepts an RSA public key of any size, but every signature-verification path decrypts into fixed-size buffers dimensioned for the `NX_CRYPTO_MAX_RSA_MODULUS_SIZE` default of 4096 bits. A certificate carrying a larger modulus drives an out-of-bounds write past a file-scope static during ordinary certificate-chain verification. It is reachable pre-authentication. The issuer used for the crypto operation is looked up in the remote, peer-supplied store before the trusted store, so the attacker supplies the oversized key themselves as an intermediate in the chain they present. It triggers on a TLS or DTLS client verifying a malicious server's chain, and on a server performing client-certificate authentication.
Affected versions
- NetX Duo
through 6.5.1.202602