CVE-2025-66559Public exploitNetwork attack vector

Verified chain corruption via cross-batch transition index

Published Dec 4, 2025 · Updated Dec 5, 2025

Improper array-index validation in Taiko Alethia 2.3.1 and earlier allows remote attackers to corrupt the verified chain pointer. TaikoInbox._verifyBatches updates tid for the current batch before verification completes, then stores that index on the preceding verified batch when the loop stops. A cooldown or invalidated transition must interrupt a linked multi-batch verification sequence, causing the preceding batch to reference a transition from the next batch.

CVSS severityUnavailable
Unscored
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper array-index validation in Taiko Alethia 2.3.1 and earlier allows remote attackers to corrupt the verified chain pointer. TaikoInbox._verifyBatches updates tid for the current batch before verification completes, then stores that index on the preceding verified batch when the loop stops. A cooldown or invalidated transition must interrupt a linked multi-batch verification sequence, causing the preceding batch to reference a transition from the next batch.

The record

CVE
CVE-2025-66559
Published
Dec 4, 2025
Updated
Dec 5, 2025
Vendor
Taiko
Product
taiko-mono
Classifications
CWE-129
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 4, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 5, 2025Record 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=<= 2.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Taiko · taiko-monoversion=<= 2.3.1

Published CVSS scores

8.0GitHub CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U

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 exploitPublished

Weakness, pattern, technique

CWE-129Improper Validation of Array Index

Public exploit references

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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