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CVE-2021-21405— BLS Signature "Malleability"

Quick assessment

Affected
filecoin-project lotus
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Łukasz Magiera lotus是Łukasz Magiera开源的一个应用软件。Filecoin分布式存储网络的实现。 Lotus 存在安全漏洞，Lotus块验证函数对所提供的块执行唯一性检查。

CVSS 5.9 · Medium EPSS 0.98% · P61

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2021-21405

Vulnerability Information
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Vulnerability Title
BLS Signature "Malleability"
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
密码学签名的验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Łukasz Magiera lotus 数据伪造问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Łukasz Magiera lotus是Łukasz Magiera开源的一个应用软件。Filecoin分布式存储网络的实现。 Lotus 存在安全漏洞，Lotus块验证函数对所提供的块执行唯一性检查。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
filecoin-project lotus < 1.5.0 -

II. Public POCs for CVE-2021-21405

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III. Intelligence Information for CVE-2021-21405

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Patches & Fixes for CVE-2021-21405 (1)

Vendor Advisories for CVE-2021-21405 (1)

Other References for CVE-2021-21405 (1)

IV. Related Vulnerabilities

Same vendor: filecoin-project
Same weakness: CWE-347

V. Comments for CVE-2021-21405

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