CVE-2026-40323Network attack vector

Proof forgery via unchecked trace-shape witnesses

Published Apr 17, 2026 · Updated Apr 17, 2026

Improper proof verification in Succinct Labs SP1 6.0.0 through 6.0.2 allows remote attackers to forge recursive proofs. The V6 recursion circuit's jagged verifier hashes row counts for commitment binding but evaluates separate, unchecked prefix-sum witnesses, allowing different trace shapes on each side. Exploitation requires a crafted shard proof; the native verifier rejects the proof, and no arbitrary-statement forgery has been demonstrated.

CVSS severity8.9
High
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper proof verification in Succinct Labs SP1 6.0.0 through 6.0.2 allows remote attackers to forge recursive proofs. The V6 recursion circuit's jagged verifier hashes row counts for commitment binding but evaluates separate, unchecked prefix-sum witnesses, allowing different trace shapes on each side. Exploitation requires a crafted shard proof; the native verifier rejects the proof, and no arbitrary-statement forgery has been demonstrated.

The record

CVE
CVE-2026-40323
Published
Apr 17, 2026
Updated
Apr 17, 2026
Vendor
Succinct Labs
Product
SP1
Classifications
CWE-354, CWE-345
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 17, 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=>= 6.0.0, < 6.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Succinct Labs · SP1version=>= 6.0.0, < 6.1.0

Published CVSS scores

8.9GitHub, Inc.CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-354Improper Validation of Integrity Check Value
CWE-345Insufficient Verification of Data Authenticity

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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