CVE-2021-21405
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.98%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- EPSS
- 0.98% probability · 60th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-347
- Affected
- filecoin/lotus
- Source
- security-advisories@github.com
References
- https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754Exploit, Third Party Advisory
- https://github.com/filecoin-project/lotus/pull/5393Patch, Third Party Advisory
- https://github.com/filecoin-project/lotus/security/advisories/GHSA-4g52-pqcj-phvhPatch, Third Party Advisory
- https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754Exploit, Third Party Advisory
- https://github.com/filecoin-project/lotus/pull/5393Patch, Third Party Advisory
- https://github.com/filecoin-project/lotus/security/advisories/GHSA-4g52-pqcj-phvhPatch, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.