CVE-2023-34451: CometBFT is a Byzantine Fault Tolerant (BFT) middleware that takes a state transition machine and replicates it on many machines. The mempool maintain...

Description

CometBFT is a Byzantine Fault Tolerant (BFT) middleware that takes a state transition machine and replicates it on many machines. The mempool maintains two data structures to keep track of outstanding transactions: a list and a map. These two data structures are supposed to be in sync all the time in the sense that the map tracks the index (if any) of the transaction in the list. In `v0.37.0`, and `v0.37.1`, as well as in `v0.34.28`, and all previous releases of the CometBFT repo2, it is possible to have them out of sync. When this happens, the list may contain several copies of the same transaction. Because the map tracks a single index, it is then no longer possible to remove all the copies of the transaction from the list. This happens even if the duplicated transaction is later committed in a block. The only way to remove the transaction is by restarting the node. The above problem can be repeated on and on until a sizable number of transactions are stuck in the mempool, in order to try to bring down the target node. The problem is fixed in releases `v0.34.29` and `v0.37.2`. Some workarounds are available. Increasing the value of `cache_size` in `config.toml` makes it very difficult to effectively attack a full node. Not exposing the transaction submission RPC's would mitigate the probability of a successful attack, as the attacker would then have to create a modified (byzantine) full node to be able to perform the attack via p2p.

Metrics

CVSS 3.1

8.2/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

EPSS Probability

0.74%

50.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Cometbft	Cometbft	>= 0.34.28, < 0.34.29
Cometbft	Cometbft	>= 0.37.0, < 0.37.2

References

https://github.com/cometbft/cometbft/pull/890Exploit, Issue Tracking, Patch
https://github.com/cometbft/cometbft/security/advisories/GHSA-w24w-wp77-qffmExploit, Mitigation, Vendor Advisory
https://github.com/tendermint/tendermint/pull/2778Issue Tracking, Patch
https://github.com/cometbft/cometbft/pull/890Exploit, Issue Tracking, Patch
https://github.com/cometbft/cometbft/security/advisories/GHSA-w24w-wp77-qffmExploit, Mitigation, Vendor Advisory
https://github.com/tendermint/tendermint/pull/2778Issue Tracking, Patch

Timeline

Published: Jul 3, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-34451?

CometBFT is a Byzantine Fault Tolerant (BFT) middleware that takes a state transition machine and replicates it on many machines. The mempool maintains two data structures to keep track of outstanding transactions: a list and a map. These two data structures are supposed to be in sync all the time in the sense that the map tracks the index (if any) of the transaction in the list. In `v0.37.0`, and `v0.37.1`, as well as in `v0.34.28`, and all previous releases of the CometBFT repo2, it is possible to have them out of sync. When this happens, the list may contain several copies of the same transaction. Because the map tracks a single index, it is then no longer possible to remove all the copies of the transaction from the list. This happens even if the duplicated transaction is later committed in a block. The only way to remove the transaction is by restarting the node. The above problem can be repeated on and on until a sizable number of transactions are stuck in the mempool, in order to try to bring down the target node. The problem is fixed in releases `v0.34.29` and `v0.37.2`. Some workarounds are available. Increasing the value of `cache_size` in `config.toml` makes it very difficult to effectively attack a full node. Not exposing the transaction submission RPC's would mitigate the probability of a successful attack, as the attacker would then have to create a modified (byzantine) full node to be able to perform the attack via p2p.

How severe is CVE-2023-34451?

CVE-2023-34451 has a CVSS score of 8.2/10 (HIGH severity). The EPSS model estimates a 0.74% probability of exploitation in the next 30 days.

How do I fix CVE-2023-34451?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.