CVE-2025-66559 Taiko Alethia Pacaya inbox verification pointer corruption
Attackers can corrupt verified chain pointers in Taiko Alethia by exploiting batch verification logic, compromising rollup integrity.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-66559?
CVE-2025-66559 is a high-severity vulnerability in taikoxyz taiko-mono, published on 4 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Taiko Alethia is an Ethereum-equivalent, permissionless, based rollup designed to scale Ethereum without compromising its fundamental properties. In 2.3.1 and earlier, TaikoInbox._verifyBatches (packages/protocol/contracts/layer1/based/TaikoInbox.sol:627-678) advanced the local tid to whatever transition matched the current blockHash before knowing whether that batch would actually be verified. When the loop later broke (e.g., cooldown window not yet passed or transition invalidated), the function still wrote that newer tid into batches[lastVerifiedBatchId].verifiedTransitionId after decrementing batchId. Result: the last verified batch could end up pointing at a transition index from the next batch (often zeroed), corrupting the verified chain pointer.
Weakness: CWE-129
Which versions are affected by CVE-2025-66559?
How do I fix CVE-2025-66559?
No fix has been published for CVE-2025-66559 yet. Limit exposure of the affected software until one is available.
Is CVE-2025-66559 being exploited?
There is no known exploitation of CVE-2025-66559 in the wild and no public exploit code.
Sources
Also known as GHSA-5mxh-r33p-6h5x.