RustCrypto's elliptic-curves library provides general-purpose elliptic curve cryptography support, including implementations of various curves and cryptographic operations. In versions 0.14.0-pre.0 and 0.14.0-rc.0, a critical vulnerability (CVE-2026-22698) was discovered in the SM2 Public Key Encryption (PKE) implementation. The root cause is a unit mismatch error in the nonce generation function, which causes it to request only 32 bits of randomness instead of the expected 256 bits. This insufficient entropy (CWE-331) drastically reduces the security of the ephemeral nonce k from a cryptographically strong 128-bit level to a trivial 16-bit level. Since the ephemeral nonce is critical for the security of SM2 encryption, this weakness allows an attacker to feasibly recover the nonce k by brute force or other cryptanalysis methods. Once the nonce is recovered, the attacker can decrypt any ciphertext encrypted under that nonce using only the public key and ciphertext, without requiring authentication or user interaction. This compromises the confidentiality of encrypted data. The vulnerability has been assigned a CVSS 4.0 score of 8.7 (high severity) due to its network attack vector, no required privileges or user interaction, and high impact on confidentiality. The issue was patched in a subsequent commit (e4f7778). No known exploits have been reported in the wild yet, but the weakness is straightforward to exploit given the drastically reduced entropy. Organizations using the affected RustCrypto versions for SM2 encryption should urgently upgrade and audit their cryptographic implementations to prevent data exposure.

The primary impact of CVE-2026-22698 is the compromise of confidentiality for data encrypted using the vulnerable SM2 PKE implementation in RustCrypto elliptic-curves versions 0.14.0-pre.0 and 0.14.0-rc.0. Attackers can recover the ephemeral nonce due to severely reduced entropy, enabling decryption of intercepted ciphertexts without needing private keys or authentication. For European organizations, this poses a significant risk to sensitive communications, intellectual property, and personal data protected by SM2 encryption. Industries such as finance, telecommunications, government, and critical infrastructure that rely on ECC for secure communications could face data breaches and regulatory non-compliance under GDPR. The vulnerability could also undermine trust in cryptographic libraries and software supply chains that incorporate RustCrypto. Although no exploits are currently known in the wild, the ease of exploitation and high confidentiality impact make this a pressing threat. Failure to patch could lead to targeted espionage, data theft, and disruption of secure services across Europe.

1. Immediately upgrade RustCrypto elliptic-curves to a patched version beyond 0.14.0-rc.0 where the nonce entropy issue is fixed (commit e4f7778 or later). 2. Audit all cryptographic implementations and dependencies to identify usage of the vulnerable versions, especially where SM2 encryption is employed. 3. Replace or re-encrypt any sensitive data encrypted with the vulnerable versions to prevent retrospective decryption. 4. Implement cryptographic best practices including using well-vetted libraries and verifying cryptographic parameters and entropy sources. 5. Monitor software supply chains and dependency updates to detect and remediate vulnerable components promptly. 6. Educate developers and security teams on the importance of entropy in cryptographic operations and the risks of unit mismatches or similar coding errors. 7. Consider deploying additional layers of encryption or key management controls to mitigate risks from compromised cryptographic primitives. 8. Engage with RustCrypto maintainers and community for updates and security advisories.