CVE-2021-38195: Libsecp256k1 Overflow Vulnerability

CRITICAL
Advisory Identifier: GHSA-g4vj-x7v9-h82m
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CVSS 9.8
CWE-190 CWE-347
Published
Advisory Summary

CVE-2021-38195 is a CRITICAL (CVSS 9.8) overflow vulnerability (CWE-190: Integer Overflow or Wraparound) affecting Libsecp256k1 libraries in the crates.io ecosystem. The issue involves overflow in libsecp256k1. Remediation is available by upgrading affected packages to version 0.5.0.

CVE-2021-38195 at a Glance

CVE Identifier CVE-2021-38195
GHSA Identifier GHSA-g4vj-x7v9-h82m
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-190: Integer Overflow or Wraparound
Affected Product Libsecp256k1
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 9.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2021-38195

To remediate this vulnerability, upgrade all affected Libsecp256k1 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

libsecp256k1 fixed: 0.5.0 
Upgrade libsecp256k1 to 0.5.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for libsecp256k1

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-38195, inspect your project dependencies for Libsecp256k1:

inspect dependencies for libsecp256k1

Analyze the terminal output to locate any version of Libsecp256k1 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.5.0), 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-190: Integer Overflow or Wraparound, where the product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. this occurs when an integer value is incremented to a value that is too large to store in the associated representation. when this occurs, the value may become a very small or negative number. In Libsecp256k1, 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

An issue was discovered in the libsecp256k1 crate before 0.5.0 for Rust. It can verify an invalid signature because it allows the R or S parameter to be larger than the curve order, aka an overflow.

CVE-2021-38195 Affected Libsecp256k1 Versions

1 component(s)
Fixed Versions:
0.5.0
Product / Package Ecosystem Affected Versions Fixed Version
libsecp256k1
 crates.io
< 0.5.0
0.5.0

References

NVD — CVE-2021-38195 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-38195
Libsecp256k1 Source Repository REPOSITORY
https://github.com/paritytech/libsecp256k1/pull/67
Libsecp256k1 Source Repository REPOSITORY
https://github.com/paritytech/libsecp256k1
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2021-0076.html

Frequently Asked Questions

What is CVE-2021-38195?
CVE-2021-38195 is a security vulnerability in Libsecp256k1 involving Overflow in libsecp256k1 under CWE-190: Integer Overflow or Wraparound.
Which Libsecp256k1 versions are affected?
Affected versions include releases prior to 0.5.0 across affected packages: libsecp256k1.
What version fixes CVE-2021-38195?
Upgrading to 0.5.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is libsecp256k1 affected?
Yes, libsecp256k1 is affected in releases prior to 0.5.0. Upgrade your dependency to 0.5.0 or later.
What is the CVSS score of CVE-2021-38195?
CVE-2021-38195 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2021-38195?
CVE-2021-38195 is classified under CWE-190: Integer Overflow or Wraparound (The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.).
How can I check crates.io dependencies for CVE-2021-38195?
Run the dependency tree command: 'inspect dependencies for libsecp256k1'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-g4vj-x7v9-h82m",
  "modified" : "2021-08-18T21:20:32Z",
  "published" : "2021-08-25T20:56:03Z",
  "aliases" : [ "CVE-2021-38195" ],
  "summary" : "Overflow in libsecp256k1",
  "details" : "An issue was discovered in the libsecp256k1 crate before 0.5.0 for Rust. It can verify an invalid signature because it allows the R or S parameter to be larger than the curve order, aka an overflow.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "libsecp256k1"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.5.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-38195"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/paritytech/libsecp256k1/pull/67"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/paritytech/libsecp256k1"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2021-0076.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-190", "CWE-347" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-18T21:20:32Z",
    "nvd_published_at" : "2021-08-08T06:15:00Z"
  }
}