CVE-2021-21405: Github.com/filecoin project/lotus BLS Signature "Malleability" Vulnerability
MODERATECVE-2021-21405 is a MODERATE (CVSS 5.9) bls signature "malleability" vulnerability (CWE-347: Improper Verification of Cryptographic Signature) affecting Github.com/filecoin project/lotus libraries in the Go ecosystem. The issue involves bls signature "malleability". Remediation is available by upgrading affected packages to version 1.5.0.
CVE-2021-21405 at a Glance
Security Impact
CVSS: 5.9
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N).
How to Fix CVE-2021-21405
To remediate this vulnerability, upgrade all affected Github.com/filecoin project/lotus dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade github.com/filecoin-project/lotus to 1.5.0Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for github.com/filecoin-project/lotusHow to Check if You Are Affected
To determine whether your application is affected by CVE-2021-21405, inspect your project dependencies for Github.com/filecoin project/lotus:
inspect dependencies for github.com/filecoin-project/lotusAnalyze the terminal output to locate any version of Github.com/filecoin project/lotus in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.5.0), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-347: Improper Verification of Cryptographic Signature, where the product does not verify, or incorrectly verifies, the cryptographic signature for data. In Github.com/filecoin project/lotus, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2021-21405 Affected Github.com/filecoin project/lotus Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
github.com/filecoin-project/lotus
|
Go |
< 1.5.0
|
1.5.0
|
References
Frequently Asked Questions
What is CVE-2021-21405?
Which Github.com/filecoin project/lotus versions are affected?
What version fixes CVE-2021-21405?
Is github.com/filecoin-project/lotus affected?
What is the CVSS score of CVE-2021-21405?
What CWE is associated with CVE-2021-21405?
How can I check Go dependencies for CVE-2021-21405?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-4g52-pqcj-phvh",
"modified" : "2021-05-20T20:51:00Z",
"published" : "2021-05-21T16:23:43Z",
"aliases" : [ "CVE-2021-21405" ],
"summary" : "BLS Signature \"Malleability\"",
"details" : "### Impact\n\n1. 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.\n2. 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.\n\nThe 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.\n\n### Patches\n\nBy 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.\nThis happened in https://github.com/filecoin-project/lotus/pull/5393\n\n\n### References\n\n- Original POC: https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Go",
"name" : "github.com/filecoin-project/lotus"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "1.5.0"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/filecoin-project/lotus/security/advisories/GHSA-4g52-pqcj-phvh"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-21405"
}, {
"type" : "WEB",
"url" : "https://github.com/filecoin-project/lotus/pull/5393"
}, {
"type" : "WEB",
"url" : "https://gist.github.com/wadeAlexC/2490d522e81a796af9efcad1686e6754"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-347" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2021-05-20T20:51:00Z",
"nvd_published_at" : "2021-04-15T22:15:00Z"
}
}