CVE-2026-1229: The CombinedMult function in the CIRCL ecc/p384 package (secp384r1 curve) produces an incorrect value for spec

Q: How do I fix CVE-2026-1229?

circl: upgrade to 1.6.3. Exact commands for each OS are on this page.

Q: Is CVE-2026-1229 being exploited?

CVE-2026-1229 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-1229 affect?

CVE-2026-1229 affects circl. Severity is critical (CVSS 9.8). 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

Q: How urgent is CVE-2026-1229?

Priority 48/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.8REMOTEUPGRADE

CVE-2026-1229 is a critical-severity flaw (CVSS 9.8) affecting circl. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 .

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 63%)
CISA exploited list	No
Weakness	CWE-682
Published	2026-02-24
Last modified	2026-06-17

Publisher (CNA): Cloudflare, Inc. · Vendor: cloudflare

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-02-24 08:16 UTCPublished CVE record published
2026-06-17 10:15 UTCUpdated Record last modified

cloudflare circl UPGRADE

Affected: < 1.6.3

Fixed in: 1.6.3

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy circl || rpm -q circl || circl --version

2. UPGRADE to 1.6.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade circl

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade circl

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Advisories and coverage

Official advisories

HashiCorp Vault Releases: v2.2.0 2026-10-15
HashiCorp Vault Releases: v2.2.0-rc1 2026-10-08

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-1229?

circl: upgrade to 1.6.3. Exact commands for each OS are on this page.

Is CVE-2026-1229 being exploited?

CVE-2026-1229 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-1229 affect?

CVE-2026-1229 affects circl. Severity is critical (CVSS 9.8). 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

How urgent is CVE-2026-1229?

Priority 48/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

GitHub vulnerabilities · Cloudflare vulnerabilities

References

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