CVE-2026-1229: Incorrect calculation in CIRCL secp384r1 CombinedMult

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-02-24 · updated 2026-06-17
Weakness: CWE-682

Description

The CombinedMult function in the CIRCL ecc/p384 package (secp384r1 curve) produces an incorrect value for specific inputs. The issue is fixed by using complete addition formulas. ECDH and ECDSA signing relying on this curve are not affected. The bug was fixed in v1.6.3 https://github.com/cloudflare/circl/releases/tag/v1.6.3 .

Affected products

Cloudflare CIRCL: before 1.6.3 — fixed in 1.6.3

How to fix

Upgrade to a fixed version: Cloudflare CIRCL 1.6.3. Check the vendor advisory for mitigations.

References

https://github.com/cloudflare/circl

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