CVE-2021-21405

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.

Related CPE's


CvssV3 impact


BaseSeverity

HIGH

ConfidentialityImpact

NONE

AttackComplexity

LOW

Scope

UNCHANGED

AttackVector

NETWORK

AvailabilityImpact

NONE

IntegrityImpact

HIGH

PrivilegesRequired

NONE

BaseScore

7.5

VectorString

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Version

3.1

UserInteraction

NONE

CvssV2 impact


AccessComplexity

LOW

ConfidentialityImpact

NONE

AvailabilityImpact

NONE

IntegrityImpact

PARTIAL

BaseScore

5

VectorString

AV:N/AC:L/Au:N/C:N/I:P/A:N

Version

2.0

AccessVector

NETWORK

Authentication

NONE