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CirclApplication · Cloudflare

CVE-2026-1229

CRITICAL · 9.8 CVSS v3.1 Published 2026-02-24
Fix available
A fix is available. Upgrade to 1.6.3 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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 .

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

The CombinedMult function in CIRCL's ecc/p384 package (secp384r1 curve) produces incorrect output values for specific inputs due to incomplete addition formulas. This affects point multiplication operations on the secp384r1 curve, though ECDH and ECDSA signing operations are explicitly not impacted by this vulnerability.

MitigationUpdate CIRCL library to v1.6.3 or later to obtain the corrected complete addition formulas. Given the critical CVSS score (9.8), prioritize this update in systems using the affected CombinedMult function for secp384r1 operations.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
CirclApplication
Affected:< 1.6.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify CIRCL library usage
    Search your codebase for 'circl' imports or check your go.mod file for 'github.com/cloudflare/circl' dependency
    Affected if The circl library is present as a dependency
  2. Check CIRCL version
    Run 'go list -m github.com/cloudflare/circl' or inspect the version listed in your go.sum file
    Affected if The version is lower than v1.6.3 (e.g., v1.6.2, v1.6.1, v1.6.0, etc.)
  3. Identify CombinedMult usage
    Search your codebase for calls to 'CombinedMult' function, typically in the pattern 'circl/ecc/p384'. Example search: grep -r 'CombinedMult' --include='*.go'
    Affected if Code calls CombinedMult from the ecc/p384 package
  4. Verify secp384r1 curve usage
    Inspect the CombinedMult calls to confirm they use the secp384r1 curve (the p384 curve). Check the context or parameters passed to CombinedMult
    Affected if The CombinedMult function is used with secp384r1 (secp384r1) curve parameters
  5. Check for point multiplication operations
    Review code paths that invoke CombinedMult to determine if point multiplication operations are performed
    Affected if Point multiplication operations using CombinedMult are executed in your application

You are affected if your application uses the CIRCL library version lower than v1.6.3 and executes point multiplication operations via the CombinedMult function with the secp384r1 curve.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.6.3 or later
Fixed in 1.6.3
Interim mitigation

Update CIRCL library to v1.6.3 or later to obtain the corrected complete addition formulas. Given the critical CVSS score (9.8), prioritize this update in systems using the affected CombinedMult function for secp384r1 operations.

Recommended fix High confidence

v1.6.3 (github.com/cloudflare/circl)

  1. Identify all codebases and dependencies that use the Circl library with version lower than 1.6.3
  2. Update the circl dependency in your go.mod or dependency management file to version 1.6.3 or later (e.g., go get github.com/cloudflare/[email protected])
  3. Run go mod tidy to clean up dependencies
  4. Rebuild the application to ensure the new library version is incorporated
  5. Redeploy the updated application to all affected environments
  6. Verify the fix by testing the CombinedMult function with the specific inputs that previously produced incorrect values

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Circl Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
16.0 hours of engineering $2,760
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-1229 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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