CVE-2021-45394: Spipu/html2pdf Cross-Site Scripting Vulnerability

HIGH
Advisory Identifier: GHSA-6m93-343m-3jrc
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CVSS 8.8
CWE-79 CWE-918
Published
Advisory Summary

CVE-2021-45394 is a HIGH (CVSS 8.8) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Spipu/html2pdf libraries in the Packagist ecosystem. The issue involves cross-site scripting in html2pdf. Remediation is available by upgrading affected packages to version 5.2.4.

CVE-2021-45394 at a Glance

CVE Identifier CVE-2021-45394
GHSA Identifier GHSA-6m93-343m-3jrc
Severity HIGH
CVSS v3.1 Base Score 8.8
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Spipu/html2pdf
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 8.8

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:R/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 Required (UI:R)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2021-45394

To remediate this vulnerability, upgrade all affected Spipu/html2pdf dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

spipu/html2pdf fixed: 5.2.4 
Upgrade spipu/html2pdf to 5.2.4
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 spipu/html2pdf

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-45394, inspect your project dependencies for Spipu/html2pdf:

inspect dependencies for spipu/html2pdf

Analyze the terminal output to locate any version of Spipu/html2pdf in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.2.4), 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 Spipu/html2pdf, 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 Spipu HTML2PDF before 5.2.4. Attackers can trigger deserialization of arbitrary data via the injection of a malicious <link> tag in the converted HTML document.

CVE-2021-45394 Affected Spipu/html2pdf Versions

1 component(s)
Fixed Versions:
5.2.4
Product / Package Ecosystem Affected Versions Fixed Version
spipu/html2pdf
 Packagist
< 5.2.4
5.2.4

References

NVD — CVE-2021-45394 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-45394
Security Fix Commit FIX COMMIT
https://github.com/spipu/html2pdf/commit/100a4d509abf8550765cf0e0da83e83abb422585
Security Fix Commit FIX COMMIT
https://github.com/spipu/html2pdf/commit/2e6bab9a2afe9cfd4d3c3038da64d8ad74e41d7f
Spipu/html2pdf Source Repository REPOSITORY
https://github.com/spipu/html2pdf
Spipu/html2pdf Source Repository REPOSITORY
https://github.com/spipu/html2pdf/blob/master/CHANGELOG.md
Spipu/html2pdf Release RELEASE
https://github.com/spipu/html2pdf/releases/tag/v5.2.4
www.synacktiv.com/sites/default/files... WEB
https://www.synacktiv.com/sites/default/files/2022-01/html2pdf_ssrf_deserialization.pdf

Frequently Asked Questions

What is CVE-2021-45394?
CVE-2021-45394 is a security vulnerability in Spipu/html2pdf involving Cross-site Scripting in HTML2PDF under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Spipu/html2pdf versions are affected?
Affected versions include releases prior to 5.2.4 across affected packages: spipu/html2pdf.
What version fixes CVE-2021-45394?
Upgrading to 5.2.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is spipu/html2pdf affected?
Yes, spipu/html2pdf is affected in releases prior to 5.2.4. Upgrade your dependency to 5.2.4 or later.
What is the CVSS score of CVE-2021-45394?
CVE-2021-45394 has a CVSS v3.1 base score of 8.8 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2021-45394?
CVE-2021-45394 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 Packagist dependencies for CVE-2021-45394?
Run the dependency tree command: 'inspect dependencies for spipu/html2pdf'. 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-6m93-343m-3jrc",
  "modified" : "2022-01-25T20:48:30Z",
  "published" : "2022-01-21T23:29:48Z",
  "aliases" : [ "CVE-2021-45394" ],
  "summary" : "Cross-site Scripting in HTML2PDF",
  "details" : "An issue was discovered in Spipu HTML2PDF before 5.2.4. Attackers can trigger deserialization of arbitrary data via the injection of a malicious <link> tag in the converted HTML document.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "spipu/html2pdf"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.2.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-45394"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/spipu/html2pdf/commit/100a4d509abf8550765cf0e0da83e83abb422585"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/spipu/html2pdf/commit/2e6bab9a2afe9cfd4d3c3038da64d8ad74e41d7f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/spipu/html2pdf"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/spipu/html2pdf/blob/master/CHANGELOG.md"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/spipu/html2pdf/releases/tag/v5.2.4"
  }, {
    "type" : "WEB",
    "url" : "https://www.synacktiv.com/sites/default/files/2022-01/html2pdf_ssrf_deserialization.pdf"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79", "CWE-918" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-01-19T22:40:38Z",
    "nvd_published_at" : "2022-01-18T12:15:00Z"
  }
}