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Fencer Vulns
high 8.2

CVE-2023-34451 json

CometBFT may duplicate transactions in the mempool's data structures

published 2023-07-03 3 y ago modified 2026-09-10 1 mo ago also GHSA-w24w-wp77-qffm , GO-2023-1883 , EUVD-2023-2155

cvss
8.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/cometbft/cometbft 0.34.29, 0.37.2
  • cometbft cometbft 0.34.29, 0.37.2

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
23 mo ago

Exploit prediction

0.90% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/cometbft/cometbft/pull/890 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/cometbft/cometbft/security/advisories/GHSA-w24w-wp77-qffm referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
NVD 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
GitHub 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Affected packages

ecosystem package affected fixed in
go github.com/cometbft/cometbft
<0.34.29
>=0.37.0, <0.37.2
<0.37.2
0.34.29
0.37.2

Affected products

  • cometbft cometbft

Classification

Weakness
  • CWE-401 Missing Release of Memory after Effective Lifetime

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.