CVE-2018-20993: Yaml rust Uncontrolled Recursion Vulnerability

HIGH
Advisory Identifier: GHSA-hv87-47h9-jcvq
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CVSS 7.5
CWE-674
Published
Advisory Summary

CVE-2018-20993 is a HIGH (CVSS 7.5) uncontrolled recursion vulnerability (CWE-674: Uncontrolled Recursion) affecting Yaml rust libraries in the crates.io ecosystem. The issue involves uncontrolled recursion in rust-yaml. Remediation is available by upgrading affected packages to version 0.4.1.

CVE-2018-20993 at a Glance

CVE Identifier CVE-2018-20993
GHSA Identifier GHSA-hv87-47h9-jcvq
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-674: Uncontrolled Recursion
Affected Product Yaml rust
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2018-20993

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

yaml-rust fixed: 0.4.1 
Upgrade yaml-rust to 0.4.1
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 yaml-rust

How to Check if You Are Affected

To determine whether your application is affected by CVE-2018-20993, inspect your project dependencies for Yaml rust:

inspect dependencies for yaml-rust

Analyze the terminal output to locate any version of Yaml rust in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.4.1), 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-674: Uncontrolled Recursion, where the product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack. In Yaml rust, 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

Affected versions of this crate did not prevent deep recursion while deserializing data structures. This allows an attacker to make a YAML file with deeply nested structures that causes an abort while deserializing it. The flaw was corrected by checking the recursion depth.

CVE-2018-20993 Affected Yaml rust Versions

1 component(s)
Fixed Versions:
0.4.1
Product / Package Ecosystem Affected Versions Fixed Version
yaml-rust
 crates.io
< 0.4.1
0.4.1

References

NVD — CVE-2018-20993 NVD
https://nvd.nist.gov/vuln/detail/CVE-2018-20993
Yaml rust Source Repository REPOSITORY
https://github.com/chyh1990/yaml-rust/pull/109
Security Fix Commit FIX COMMIT
https://github.com/chyh1990/yaml-rust/commit/d61b49cb90391fc4f7f72a1abe597476c8651a07
Yaml rust Source Repository REPOSITORY
https://github.com/chyh1990/yaml-rust
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2018-0006.html

Frequently Asked Questions

What is CVE-2018-20993?
CVE-2018-20993 is a security vulnerability in Yaml rust involving Uncontrolled recursion in rust-yaml under CWE-674: Uncontrolled Recursion.
Which Yaml rust versions are affected?
Affected versions include releases prior to 0.4.1 across affected packages: yaml-rust.
What version fixes CVE-2018-20993?
Upgrading to 0.4.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is yaml-rust affected?
Yes, yaml-rust is affected in releases prior to 0.4.1. Upgrade your dependency to 0.4.1 or later.
What is the CVSS score of CVE-2018-20993?
CVE-2018-20993 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2018-20993?
CVE-2018-20993 is classified under CWE-674: Uncontrolled Recursion (The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.).
How can I check crates.io dependencies for CVE-2018-20993?
Run the dependency tree command: 'inspect dependencies for yaml-rust'. 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-hv87-47h9-jcvq",
  "modified" : "2023-06-13T22:23:08Z",
  "published" : "2021-08-25T20:43:13Z",
  "aliases" : [ "CVE-2018-20993" ],
  "summary" : "Uncontrolled recursion in rust-yaml",
  "details" : "Affected versions of this crate did not prevent deep recursion while deserializing data structures. This allows an attacker to make a YAML file with deeply nested structures that causes an abort while deserializing it. The flaw was corrected by checking the recursion depth.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "yaml-rust"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.4.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2018-20993"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/chyh1990/yaml-rust/pull/109"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/chyh1990/yaml-rust/commit/d61b49cb90391fc4f7f72a1abe597476c8651a07"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/chyh1990/yaml-rust"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2018-0006.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-674" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-19T21:24:44Z",
    "nvd_published_at" : null
  }
}