CVE-2019-20399: Libsecp256k1 rs Observable Discrepancy Vulnerability

MODERATE
Advisory Identifier: GHSA-7cqg-8449-rmfv
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CVSS 5.9
CWE-362 CWE-203
Published
Advisory Summary

CVE-2019-20399 is a MODERATE (CVSS 5.9) observable discrepancy vulnerability (CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')) affecting Libsecp256k1 rs libraries in the crates.io ecosystem. The issue involves observable discrepancy in libsecp256k1-rs. Remediation is available by upgrading affected packages to version 0.3.1.

CVE-2019-20399 at a Glance

CVE Identifier CVE-2019-20399
GHSA Identifier GHSA-7cqg-8449-rmfv
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Affected Product Libsecp256k1 rs
Package Ecosystem crates.io
Published Date
Last Updated

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:H/I:N/A:N).

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

How to Fix CVE-2019-20399

To remediate this vulnerability, upgrade all affected Libsecp256k1 rs 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-rs fixed: 0.3.1 
Upgrade libsecp256k1-rs to 0.3.1
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-rs

How to Check if You Are Affected

To determine whether your application is affected by CVE-2019-20399, inspect your project dependencies for Libsecp256k1 rs:

inspect dependencies for libsecp256k1-rs

Analyze the terminal output to locate any version of Libsecp256k1 rs in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.3.1), 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-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition'), where the product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently. In Libsecp256k1 rs, 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

A timing vulnerability in the Scalar::check_overflow function in Parity libsecp256k1-rs before 0.3.1 potentially allows an attacker to leak information via a side-channel attack.

CVE-2019-20399 Affected Libsecp256k1 rs Versions

1 component(s)
Fixed Versions:
0.3.1
Product / Package Ecosystem Affected Versions Fixed Version
libsecp256k1-rs
 crates.io
< 0.3.1
0.3.1

References

NVD — CVE-2019-20399 NVD
https://nvd.nist.gov/vuln/detail/CVE-2019-20399
Security Fix Commit FIX COMMIT
https://github.com/paritytech/libsecp256k1/commit/11ba23a9766a5079918cd9f515bc100bc8164b50
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2020-0156.html

Frequently Asked Questions

What is CVE-2019-20399?
CVE-2019-20399 is a security vulnerability in Libsecp256k1 rs involving Observable Discrepancy in libsecp256k1-rs under CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition').
Which Libsecp256k1 rs versions are affected?
Affected versions include releases prior to 0.3.1 across affected packages: libsecp256k1-rs.
What version fixes CVE-2019-20399?
Upgrading to 0.3.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is libsecp256k1-rs affected?
Yes, libsecp256k1-rs is affected in releases prior to 0.3.1. Upgrade your dependency to 0.3.1 or later.
What is the CVSS score of CVE-2019-20399?
CVE-2019-20399 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2019-20399?
CVE-2019-20399 is classified under CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') (The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.).
How can I check crates.io dependencies for CVE-2019-20399?
Run the dependency tree command: 'inspect dependencies for libsecp256k1-rs'. 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-7cqg-8449-rmfv",
  "modified" : "2021-07-27T15:21:02Z",
  "published" : "2021-08-25T21:01:27Z",
  "aliases" : [ "CVE-2019-20399" ],
  "summary" : "Observable Discrepancy in libsecp256k1-rs",
  "details" : "A timing vulnerability in the Scalar::check_overflow function in Parity libsecp256k1-rs before 0.3.1 potentially allows an attacker to leak information via a side-channel attack.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "libsecp256k1-rs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.3.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2019-20399"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/paritytech/libsecp256k1/commit/11ba23a9766a5079918cd9f515bc100bc8164b50"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2020-0156.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-203", "CWE-362" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-07-27T15:21:02Z",
    "nvd_published_at" : "2020-01-23T00:15:00Z"
  }
}