GHSA-gfxp-f68g-8x78: LibYML `libyml::string::yaml_string_extend` Is Unsound And Unmaintained Vulnerability

HIGH
Share
CWE-758
Published
Advisory Summary

GHSA-gfxp-f68g-8x78 is a HIGH `libyml::string::yaml_string_extend` is unsound and unmaintained vulnerability (CWE-758: Reliance on Undefined, Unspecified, or Implementation-Defined Behavior) affecting LibYML libraries in the crates.io ecosystem. The issue involves `libyml::string::yaml_string_extend` is unsound and unmaintained. Remediation is available in the latest vendor maintenance releases.

GHSA-gfxp-f68g-8x78 at a Glance

CVE Identifier N/A
GHSA Identifier GHSA-gfxp-f68g-8x78
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-758: Reliance on Undefined, Unspecified, or Implementation-Defined Behavior
Affected Product LibYML
Package Ecosystem crates.io
Published Date
Last Updated

How to Fix GHSA-gfxp-f68g-8x78

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

libyml fixed: Latest secure release 
Upgrade libyml to Latest secure release
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 libyml

How to Check if You Are Affected

To determine whether your application is affected by GHSA-gfxp-f68g-8x78, inspect your project dependencies for LibYML:

inspect dependencies for libyml

Analyze the terminal output to locate any version of LibYML in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), 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-758: Reliance on Undefined, Unspecified, or Implementation-Defined Behavior, where the product uses an api function, data structure, or other entity in a way that relies on properties that are not always guaranteed to hold for that entity. In LibYML, 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

In version 0.0.4, `libyml::string::yaml_string_extend` was revised resulting in undefined behaviour, which is unsound. The GitHub project for `libyml` was archived after unsoundness issues were raised. If you rely on this crate, it is highly recommended switching to a maintained alternative. ## Recommended alternatives - [`libyaml-safer`](https://crates.io/crates/libyaml-safer) - [`unsafe-libyaml-norway`](https://crates.io/crates/unsafe-libyaml-norway) - Maintained fork of `unsafe-libyaml`

GHSA-gfxp-f68g-8x78 Affected LibYML Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
libyml
 crates.io
≥ 0.0.4
≤ 0.0.5

References

LibYML Source Repository REPOSITORY
https://github.com/rustsec/advisory-db/issues/2395
LibYML Source Repository REPOSITORY
https://github.com/sebastienrousseau/libyml
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2025-0067.html

Frequently Asked Questions

What is GHSA-gfxp-f68g-8x78?
GHSA-gfxp-f68g-8x78 is a security vulnerability in LibYML involving `libyml::string::yaml_string_extend` is unsound and unmaintained under CWE-758: Reliance on Undefined, Unspecified, or Implementation-Defined Behavior.
Which LibYML versions are affected?
Affected versions include releases prior to current release patches across affected packages: libyml.
What version fixes GHSA-gfxp-f68g-8x78?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is libyml affected?
Yes, libyml is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What CWE is associated with GHSA-gfxp-f68g-8x78?
GHSA-gfxp-f68g-8x78 is classified under CWE-758: Reliance on Undefined, Unspecified, or Implementation-Defined Behavior (The product uses an API function, data structure, or other entity in a way that relies on properties that are not always guaranteed to hold for that entity.).
How can I check crates.io dependencies for GHSA-gfxp-f68g-8x78?
Run the dependency tree command: 'inspect dependencies for libyml'. 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-gfxp-f68g-8x78",
  "modified" : "2025-09-15T13:57:29Z",
  "published" : "2025-09-15T13:57:29Z",
  "aliases" : [ ],
  "summary" : "LibYML: `libyml::string::yaml_string_extend` is unsound and unmaintained",
  "details" : "In version 0.0.4, `libyml::string::yaml_string_extend` was revised resulting in undefined behaviour, which is unsound.\n\nThe GitHub project for `libyml` was archived after unsoundness issues were raised.\n\nIf you rely on this crate, it is highly recommended switching to a maintained alternative.\n\n## Recommended alternatives\n\n- [`libyaml-safer`](https://crates.io/crates/libyaml-safer) \n- [`unsafe-libyaml-norway`](https://crates.io/crates/unsafe-libyaml-norway) - Maintained fork of `unsafe-libyaml`",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "libyml"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.0.4"
      }, {
        "last_affected" : "0.0.5"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/rustsec/advisory-db/issues/2395"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/sebastienrousseau/libyml"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2025-0067.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-758" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-09-15T13:57:29Z",
    "nvd_published_at" : null
  }
}