CVE-2026-1229Network attack vector

Incorrect P-384 results via incomplete point addition

Published Feb 24, 2026 · Updated Feb 24, 2026

Incorrect calculation in Cloudflare CIRCL before 1.6.3 allows remote attackers to produce wrong P-384 results via crafted CombinedMult inputs. The ecc/p384 Jacobian point-addition path applies an incomplete addition formula when both operands represent the same point, so a required doubling case returns the wrong curve point. Reachability requires a consuming application to pass attacker-controlled inputs to CombinedMult; ECDH and ECDSA signing on this curve are unaffected.

CVSS severity9.8
Critical
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect calculation in Cloudflare CIRCL before 1.6.3 allows remote attackers to produce wrong P-384 results via crafted CombinedMult inputs. The ecc/p384 Jacobian point-addition path applies an incomplete addition formula when both operands represent the same point, so a required doubling case returns the wrong curve point. Reachability requires a consuming application to pass attacker-controlled inputs to CombinedMult; ECDH and ECDSA signing on this curve are unaffected.

The record

CVE
CVE-2026-1229
Published
Feb 24, 2026
Updated
Feb 24, 2026
Vendor
Cloudflare
Product
CIRCL
Classifications
CWE-682
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=CIRCL up to version 1.6.2 <1.6.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Cloudflare · CIRCLversion=CIRCL up to version 1.6.2 <1.6.3

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
2.9CloudflareCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L/E:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-682Incorrect Calculation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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