CVE-2021-38193: Ammonia Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-5325-xw5m-phm3
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CVSS 6.1
CWE-79
Published
Advisory Summary

CVE-2021-38193 is a MODERATE (CVSS 6.1) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Ammonia libraries in the crates.io ecosystem. The issue involves cross-site scripting in ammonia. Remediation is available by upgrading affected packages to version 3.1.0, 2.1.3.

CVE-2021-38193 at a Glance

CVE Identifier CVE-2021-38193
GHSA Identifier GHSA-5325-xw5m-phm3
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Ammonia
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 6.1

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:R/S:C/C:L/I:L/A:N).

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

How to Fix CVE-2021-38193

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

ammonia fixed: 3.1.0 
Upgrade ammonia to 3.1.0
ammonia fixed: 2.1.3 
Upgrade ammonia to 2.1.3
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 ammonia

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-38193, inspect your project dependencies for Ammonia:

inspect dependencies for ammonia

Analyze the terminal output to locate any version of Ammonia in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.1.0), 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-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Ammonia, 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 ammonia crate before 3.1.0 for Rust. XSS can occur because the parsing differences for HTML, SVG, and MathML are mishandled, a similar issue to CVE-2020-26870.

CVE-2021-38193 Affected Ammonia Versions

2 component(s)
Fixed Versions:
3.1.02.1.3
Product / Package Ecosystem Affected Versions Fixed Version
ammonia
 crates.io
≥ 3.0.0
< 3.1.0
3.1.0
ammonia
 crates.io
< 2.1.3
2.1.3

References

NVD — CVE-2021-38193 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-38193
Ammonia Source Repository REPOSITORY
https://github.com/rust-ammonia/ammonia/pull/142
Ammonia Source Repository REPOSITORY
https://github.com/rust-ammonia/ammonia
raw.githubusercontent.com/rustsec/advisory-db... WEB
https://raw.githubusercontent.com/rustsec/advisory-db/main/crates/ammonia/RUSTSEC-2021-0074.md
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2021-0074.html

Frequently Asked Questions

What is CVE-2021-38193?
CVE-2021-38193 is a security vulnerability in Ammonia involving Cross-site Scripting in ammonia under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Ammonia versions are affected?
Affected versions include releases prior to 3.1.0, 2.1.3 across affected packages: ammonia.
What version fixes CVE-2021-38193?
Upgrading to 3.1.0, 2.1.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is ammonia affected?
Yes, ammonia is affected in releases prior to 3.1.0, 2.1.3. Upgrade your dependency to 3.1.0, 2.1.3 or later.
What is the CVSS score of CVE-2021-38193?
CVE-2021-38193 has a CVSS v3.1 base score of 6.1 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2021-38193?
CVE-2021-38193 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check crates.io dependencies for CVE-2021-38193?
Run the dependency tree command: 'inspect dependencies for ammonia'. 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-5325-xw5m-phm3",
  "modified" : "2021-08-18T21:28:38Z",
  "published" : "2021-08-25T20:55:56Z",
  "aliases" : [ "CVE-2021-38193" ],
  "summary" : "Cross-site Scripting in ammonia",
  "details" : "An issue was discovered in the ammonia crate before 3.1.0 for Rust. XSS can occur because the parsing differences for HTML, SVG, and MathML are mishandled, a similar issue to CVE-2020-26870.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "ammonia"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.0.0"
      }, {
        "fixed" : "3.1.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "ammonia"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.1.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-38193"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rust-ammonia/ammonia/pull/142"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/rust-ammonia/ammonia"
  }, {
    "type" : "WEB",
    "url" : "https://raw.githubusercontent.com/rustsec/advisory-db/main/crates/ammonia/RUSTSEC-2021-0074.md"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2021-0074.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-18T21:28:38Z",
    "nvd_published_at" : "2021-08-08T06:15:00Z"
  }
}