Executive brief
A vulnerability was identified in the Linux kernel's cryptographic library specifically affecting Elliptic Curve Cryptography (ECC) operations. This flaw could potentially lead to incorrect mathematical calculations during secure data processing, which might impact the reliability of encrypted communications or digital signatures. The issue has been resolved in recent kernel updates.
Technical details
A vulnerability in 'crypto/ecc.c' of the Linux kernel was caused by an incorrect carry flag calculation during variable-length integer (VLI) multiplication. Specifically, the 'add_128_128' helper failed to account for a carry bit when the high-order 64 bits were saturated and the lower-bit addition overflowed. This logic error was introduced during the porting of the micro-ecc library. An attacker could potentially exploit this to cause incorrect ECC results, affecting ECDH and other ECC-based protocols. The fix replaces the flawed logic with a constant-time overflow check to prevent both calculation errors and potential timing side-channels.
Affected products
- Linux Linux Kernel 4.8 to 6.10.y
Timeline
- 2026-07-25: advisory: CVE-2026-64313 published
- 2026-05-13: patched: Initial fix authored
References
- https://git.kernel.org/stable/c/24a54dfa06d09813b4802a374fad3d2c0e16a884
- https://git.kernel.org/stable/c/27b536a2ec8e2f85a0380c2d13c9ecbc7aaab406
- https://git.kernel.org/stable/c/5275e0fca256d081e2e7d4ba3dd8216c6e50d44e
- https://git.kernel.org/stable/c/677450e5ef850c4d28b7956aa01104548c2a894e
- https://git.kernel.org/stable/c/774ddddf5eb26eeca177350413e3e2bc50930ee9
- https://git.kernel.org/stable/c/b709e0e768766abe29a49e1c1922a1604be602f4
- https://git.kernel.org/stable/c/d11b2bb99bec1f5557c01cac42231e23745f49b8