btcd: Always-Incorrect Control Flow Implementation
CVE-2024-38365 is a high-severity always-incorrect control flow implementation vulnerability in btcd from Btcsuite, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected btcd versions: >= 0.10.0, < 0.24.2. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.01% chance of exploitation within 30 days, higher than 64% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of btcd you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.4 | High | CNA (github.com) |
| CVSS 3.1 | 8.1 | High | NVD |
Official description
btcd is an alternative full node bitcoin implementation written in Go (golang). The btcd Bitcoin client (versions 0.10 to 0.24) did not correctly re-implement Bitcoin Core's "FindAndDelete()" functionality. This logic is consensus-critical: the difference in behavior with the other Bitcoin clients can lead to btcd clients accepting an invalid Bitcoin block (or rejecting a valid one). This consensus failure can be leveraged to cause a chain split (accepting an invalid Bitcoin block) or be exploited to DoS the btcd nodes (rejecting a valid Bitcoin block). An attacker can create a standard transaction where FindAndDelete doesn't return a match but removeOpCodeByData does making btcd get a different sighash, leading to a chain split. Importantly, this vulnerability can be exploited remotely by any Bitcoin user and does not require any hash power. This is because the difference in behavior can be triggered by a "standard" Bitcoin transaction, that is a transaction which gets relayed through the P2P network before it gets included in a Bitcoin block. `removeOpcodeByData(script []byte, dataToRemove []byte)` removes any data pushes from `script` that contain `dataToRemove`. However, `FindAndDelete` only removes exact matches. So for example, with `script = "<data> <data||foo>"` and `dataToRemove = "data"` btcd will remove both data pushes but Bitcoin Core's `FindAndDelete` only removes the first `<data>` push. This has been patched in btcd version v0.24.2. Users are advised to upgrade. There are no known workarounds for this issue.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Always-Incorrect Control Flow Implementation
The code contains a control flow path that does not reflect the algorithm that the path is intended to implement, leading to incorrect behavior any time this path is navigated.
More Always-Incorrect Control Flow Implementation vulnerabilities (CWE-670)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
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