# GHSA-r3r4-g7hq-pq4f: CometBFT allows a malicious peer to stall the network by disseminating seemingly valid block parts > A malicious peer can stall the CometBFT network by disseminating invalid block parts, causing a denial of service for validators and full nodes. - **Severity:** Not scored - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 3 Feb 2025 - **Also known as:** GO-2025-3443 ## What is GHSA-r3r4-g7hq-pq4f? GHSA-r3r4-g7hq-pq4f is a denial of service vulnerability in github.com/cometbft/cometbft, published on 3 Feb 2025. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description Name: ASA-2025-002: Malicious peer can stall network by disseminating seemingly valid block parts Component: CometBFT Criticality: High (Catastrophic Impact; Possible Likelihood per [ACMv1.2](https://github.com/interchainio/security/blob/main/resources/CLASSIFICATION_MATRIX.md)) Affected versions: <= v0.38.16, v1.0.0 Affected users: Validators, Full nodes, Users ### Description A bug was identified in the CometBFT validation of block part indices and the corresponding proof part indices that can lead to incorrect processing and dissemination of invalid parts, which in turn could lead to a network halt. Additional validation was added to prevent this condition from happening. ### Patches The new CometBFT releases [v1.0.1](https://github.com/cometbft/cometbft/releases/tag/v1.0.1) and [v0.38.17](https://github.com/cometbft/cometbft/releases/tag/v0.38.17) fix this issue. Unreleased code in the main branch is patched as well. ### Workarounds There are no known workarounds for this issue. If a node is producing these malicious proofs, the only mitigation is to upgrade CometBFT. After upgrading, the validators then will eventually conclude the correct value. ### Technical Deep-Dive When the next proposer creates a block, it is split into many block parts (64kB each). Each block part is then disseminated via p2p layer in a gossip fashion. The block part contains the following fields: ```go type Part struct { Index uint32 `json:"index"` Bytes cmtbytes.HexBytes `json:"bytes"` Proof merkle.Proof `json:"proof"` } ``` - `Index` - represents the index of a block part - `Bytes` - the actual content - `Proof` - Merkle proof, which allows the receiving node to quickly verify that a `Part` is indeed a piece of the proposed block. The `Proof` contains the following fields: ```go type Proof struct { Total int64 `json:"total"` // Total number of items. Index int64 `json:"index"` // Index of item to prove. LeafHash []byte `json:"leaf_hash"` // Hash of item value. Aunts [][]byte `json:"aunts,omitempty"` // Hashes from leaf's sibling to a root's child. } ``` Note that the total number of leaves in the Merkle tree equals the number of parts in the proposed block. Previously, CometBFT did not validate the `Index` field and specifically that `Part.Index` must be equal to `Part.Proof.Index`. This leads to a condition where, it is possible to use the proof from a different part and CometBFT accept it, even though the proof proves the different part is a piece of the proposed block and not the part that the peer actually sent to us. This condition is problematic because: 1. it would disseminate the invalid block part to its neighboring nodes (because it deemed it as correct) 2. it would mark the block part as received and ask the neighboring nodes not to relay it in the future, making it impossible to receive the correct block part. To address this, CometBFT was patched to verify that `Part.Index` is equal to `Part.Proof.Index`, preventing the above condition. ### Timeline * January 15, 2025, 12:12pm PST: Issue reported to the Cosmos Bug Bounty program * January 15, 2025, 12:31pm PST: Issue triaged by Amulet on-call, and distributed to Core team * January 27, 2025, 11:28pm PST: Core team completes validation of issue * January 31, 2024, 2:15pm PST: Pre-notification delivered * February 3rd, 2024, 9:00am UTC+4: Patch made available This issue was reported by [unknown_feature](https://github.com/unknownfeature) to the Cosmos Bug Bounty Program on HackerOne on January 15, 2025. If you believe you have found a bug in the Interchain Stack or would like to contribute to the program by reporting a bug, please see https://hackerone.com/cosmos. If you have questions about Interchain security efforts, please reach out to our official communication channel at [security@interchain.io](mailto:security@interchain.io). For more information about the Interchain Foundation’s engagement with Amulet, and to sign up for security notification emails, please see https://github.com/interchainio/security. A Github Security Advisory for this issue is available in the CometBFT [repository](https://github.com/cometbft/cometbft/security/advisories/GHSA-r3r4-g7hq-pq4f). For more information about CometBFT, see https://docs.cometbft.com/. ## Which versions are affected by GHSA-r3r4-g7hq-pq4f? 5 open source packages ship an affected version, including github.com/cometbft/cometbft. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `github.com/cometbft/cometbft` | Go | All versions | 0.38.17, 1.0.1 | | `github.com/cometbft/cometbft` | Go | All versions | 0.38.17 | | `github.com/cometbft/cometbft` | Go | All versions | 0.38.17 | | `github.com/cometbft/cometbft` | Go | From 1.0.0-alpha.1 | 1.0.1 | | `github.com/cometbft/cometbft` | Go | From 1.0.0-alpha.1 | 1.0.1 | ## How do I fix GHSA-r3r4-g7hq-pq4f? Upgrade github.com/cometbft/cometbft to a fixed version for your release line: 0.38.17 or 1.0.1. ## Is GHSA-r3r4-g7hq-pq4f being exploited? There is no known exploitation of GHSA-r3r4-g7hq-pq4f in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for GHSA-r3r4-g7hq-pq4f and fix it if it is affected. What it is: GHSA-r3r4-g7hq-pq4f is a denial of service vulnerability in github.com/cometbft/cometbft, published on 3 Feb 2025. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of GHSA-r3r4-g7hq-pq4f in the wild and no public exploit code. Affected packages and fixed versions: - github.com/cometbft/cometbft (Go): affected all versions; fixed in 0.38.17, 1.0.1 - github.com/cometbft/cometbft (Go): affected all versions; fixed in 0.38.17 - github.com/cometbft/cometbft (Go): affected all versions; fixed in 0.38.17 - github.com/cometbft/cometbft (Go): affected from 1.0.0-alpha.1; fixed in 1.0.1 - github.com/cometbft/cometbft (Go): affected from 1.0.0-alpha.1; fixed in 1.0.1 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/GHSA-r3r4-g7hq-pq4f/ (Markdown: https://insights.sbomify.com/GHSA-r3r4-g7hq-pq4f/index.md) ``` ## Sources - OSV: https://osv.dev/vulnerability/GHSA-r3r4-g7hq-pq4f --- From sbomify Insights: https://insights.sbomify.com/GHSA-r3r4-g7hq-pq4f/ Summaries are generated and may contain mistakes; the official description above is the record.