CVE-2026-22698

RustCrypto SM2-PKE has 32-bit Biased Nonce Vulnerability

RustCrypto: Elliptic Curves is general purpose Elliptic Curve Cryptography (ECC) support, including types and traits for representing various elliptic curve forms, scalars, points, and public/secret keys composed thereof. In versions 0.14.0-pre.0 and 0.14.0-rc.0, a critical vulnerability exists in the SM2 Public Key Encryption (PKE) implementation where the ephemeral nonce k is generated with severely reduced entropy. A unit mismatch error causes the nonce generation function to request only 32 bits of randomness instead of the expected 256 bits. This reduces the security of the encryption from a 128-bit level to a trivial 16-bit level, allowing a practical attack to recover the nonce k and decrypt any ciphertext given only the public key and ciphertext. This issue has been patched via commit e4f7778.

Affected

RustCrypto · elliptic-curves

CVSS v4.0 GITHUB

8.7 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v4.0 GitHub

8.7 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS v3.1 NVD

7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

0.27% chance of exploitation in the next 30 days, 19th percentile

Published

2026-01-10

Updated

2026-01-12

Proof-of-concept exploits (1)

• advisories/GHSA-w3g8-fp6j-wvqw

Security advisories

• RustCrypto/elliptic-curves/security/advisories/GHSA-w3g8-fp6j-wvqw
• RustCrypto/elliptic-curves/pull/1600
• https://crates.io/crates/sm2/0.14.0-pre.0
• https://crates.io/crates/sm2/0.14.0-rc.0

References

• CVE Record
• NVD entry