Solana’s 50,000 SOL security contest did not cover a clock attack disclosed months earlier
At USENIX Security on Aug. 12, researchers offered a Solana Proof-of-History clock attack they’d disclosed privately to Solana builders in December 2025. Anza’s 50,000 SOL Alpenglow competitors closed seven days later, and its guidelines seem to put the attack outdoors the scope.
The paper describes a protocol-valid method for a scheduled chief to stretch its efficient block window and suppress trustworthy leaders’ proposals in a fork-assisted model. The path depends on Proof-of-History and TowerBFT, the equipment Alpenglow is meant to switch however had not but displaced on mainnet in Agave 4.2.
The finding creates each a contest-scope story and a transition-risk query.
The competition rules excluded conduct reachable solely when Alpenglow was inactive. Public design paperwork point out that the paper’s actual legacy path ought to grow to be unreachable after activation, however Anza and the Solana Foundation have not printed a paper-specific adjudication or implementation evaluation.
How a chief can stretch Solana’s clock
Proof-of-History (PoH) makes use of a sequential hash chain to present Solana a logical clock. Validators proceed advancing their native view of that clock when a scheduled chief does not instantly publish a block.
The researchers say a malicious scheduled chief can withhold a protocol-valid block whereas trustworthy validators transfer forward, then launch the block anchored to an earlier level in logical time. If validators undertake that department, they align their PoH state to the block’s earlier level. The researchers name the reset “re-anchoring.”
Time Inflation (TI) repeats that maneuver to present the attacker extra bodily time to decide on transactions whereas logical time advances extra slowly, and Fork-Assisted Time Inflation (FTI) combines the reset with TowerBFT fork alternative.
Under the modeled circumstances, the attacker’s department can orphan an trustworthy chief’s block, and Solana’s one-block-per-slot rule prevents that chief from merely producing one other block for a similar slot.
The risk mannequin provides the adversary lower than 33% of stake and no management over the community scheduler. It assumes a recognized, stake-weighted chief schedule, partial synchrony, and supply of an trustworthy block to trustworthy validators inside one nominal slot after the community stabilizes.
For an attacker controlling ℓ consecutive four-slot chief rounds, the experiments use a conservative, stake-agnostic most delay of 4ℓ + 1 slot models. One spherical maps to a five-slot-unit delay parameter.
The paper says extra stake may widen a risk-free launch window, however does not current that experimental setting as a common mainnet outcome.
The researchers carried out TI and FTI on a native Solana testnet and used simulations for full-epoch attacker configurations. They did not establish a particular affected Agave launch, so the paper does not set up that each present consumer model is uncovered in the identical method.
What public knowledge reveals
The researchers additionally studied public mainnet knowledge and chosen two validators that repeatedly sat within the tail of the timestamp-interval distribution. Those validators paired longer intervals with increased transaction inclusion and low skip charges.
The sample is in keeping with TI’s incentive channel as a result of a longer bodily window creates extra alternatives to pick fee-bearing transactions.
The paper says {hardware} variations, native batching or different configuration decisions, community circumstances, and operational disruptions may create related timing patterns. It additionally discovered no considerably elevated downstream skip charge and mentioned the noticed sample was inconsistent with attribution to FTI.
The analysis establishes a protocol-valid equity and latency difficulty by way of managed assessments and suggestive measurements. It stops in need of exhibiting a reside exploit, theft, demonstrated mainnet manipulation, or a consensus-safety break.
Why the Solana Alpenglow contest in all probability excluded it
Alpenglow competitors submissions closed Aug. 19 at 16:00 UTC. The guidelines lined the Alpenglow feature-active consensus floor, integration code whose conduct modified as a result of Alpenglow was energetic, and the TowerBFT-to-Alpenglow migration path.
Behavior reachable solely when Alpenglow was inactive belonged to the TowerBFT area and was outdoors the competitors. Previously public points had been additionally ineligible.
| Question | Legacy PoH and TowerBFT path | Alpenglow path |
|---|---|---|
| Core consensus | PoH-derived logical time with TowerBFT voting and fork alternative | Votor voting, block manufacturing, and finality with native timeouts |
| Paper’s mechanism | Uses PoH re-anchoring and legacy fork-choice conduct | Designed to make that actual path unreachable, with out a public paper-specific adjudication |
| Competition therapy | Excluded when reachable solely with Alpenglow inactive | Feature-active conduct and migration code had been in scope |
| Mainnet transition | Relevant whereas legacy consensus stays energetic | Code was current in Agave 4.2 however not activated on mainnet |
The competitors lined faults attributable to Alpenglow or its migration, and the paper targets the legacy time and fork-choice mannequin Alpenglow is supposed to switch.
What Alpenglow adjustments
Anza’s Alpenglow overview says the improve replaces TowerBFT and PoH as core consensus parts with Votor. The official SIMD-0326 proposal describes native timeouts that carry out a timing position with out synchronized time and calls the change backward-incompatible.
Those designs take away the PoH re-anchoring and TowerBFT fork-choice stipulations TI and FTI use. The public document lacks an Anza or Solana Foundation evaluation mapping every attack step onto transport Alpenglow code or ruling out a similar difficulty in migration logic.
According to the researchers, the Solana growth crew responded inside someday of the December 2025 disclosure. The paper says the crew thought-about the conduct recognized internally, anticipated a future protocol improve equivalent to Alpenglow to handle it, monitored for it, and regarded probably the most extreme situations as unlikely beneath present circumstances.
The authors additionally mentioned they’d not totally deployed mitigation by publication.
A Solana Foundation overview of Agave 4.2 mentioned the consumer included Alpenglow code for group check clusters however did not activate the brand new consensus on mainnet, with activation anticipated in Agave 4.3.
The paper’s legacy PoH attack seems to have fallen outdoors the 50,000 SOL contest, and Alpenglow is designed to take away its actual stipulations. Until activation and a public implementation-level response, the transition stays the unresolved a part of the story.
The put up Solana’s 50,000 SOL security contest did not cover a clock attack disclosed months earlier appeared first on CryptoSlate.
