Vulnerability · Published Apr 15, 2021 · Assigned by GitHub_M
CVE-2021-21405BLS Signature "Malleability"
Medium 5.9
In plain English
A medium-severity security flaw in lotus from filecoin-project. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.0% (higher than 62% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Lotus is an Implementation of the Filecoin protocol written in Go. BLS signature validation in lotus uses blst library method VerifyCompressed. This method accepts signatures in 2 forms: "serialized", and "compressed", meaning that BLS signatures can be provided as either of 2 unique byte arrays. Lotus block validation functions perform a uniqueness check on provided blocks. Two blocks are considered distinct if the CIDs of their blockheader do not match. The CID method for blockheader includes the BlockSig of the block. The result of these issues is that it would be possible to punish miners for valid blocks, as there are two different valid block CIDs available for each block, even though this must be unique. By switching from the go based `blst` bindings over to the bindings in `filecoin-ffi`, the code paths now ensure that all signatures are compressed by size and the way they are deserialized. This happened in https://github.com/filecoin-project/lotus/pull/5393.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/filecoin-project/lotus | 1.5.0 | GHSA-4g52-pqcj-phvh |
| Go | github.com/filecoin-project/lotus | 1.5.0 | GO-2022-0905 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| filecoin-project | lotus | < 1.5.0 |
Weakness: CWE-347 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
References
- https://github.com/filecoin-project/lotus/security/advisories/GHSA-4g52-pqcj-phvh x_refsource_CONFIRM
- https://github.com/filecoin-project/lotus/pull/5393 x_refsource_MISC
- https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754 x_refsource_MISC