CVE-2021-3838: Dompdf/dompdf Deserialization Of Untrusted Data Vulnerability

CRITICAL
Advisory Identifier: GHSA-577p-7j7h-2jgf
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CVSS 9.8
CWE-502
Published
Advisory Summary

CVE-2021-3838 is a CRITICAL (CVSS 9.8) deserialization of untrusted data vulnerability (CWE-502: Deserialization of Untrusted Data) affecting Dompdf/dompdf libraries in the Packagist ecosystem. The issue involves deserialization of untrusted data in dompdf/dompdf. Remediation is available by upgrading affected packages to version 2.0.0.

CVE-2021-3838 at a Glance

CVE Identifier CVE-2021-3838
GHSA Identifier GHSA-577p-7j7h-2jgf
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-502: Deserialization of Untrusted Data
Affected Product Dompdf/dompdf
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 9.8

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:N/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 None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2021-3838

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

dompdf/dompdf fixed: 2.0.0 
Upgrade dompdf/dompdf to 2.0.0
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 dompdf/dompdf

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-3838, inspect your project dependencies for Dompdf/dompdf:

inspect dependencies for dompdf/dompdf

Analyze the terminal output to locate any version of Dompdf/dompdf in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.0.0), 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-502: Deserialization of Untrusted Data, where the product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid. In Dompdf/dompdf, 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

DomPDF before version 2.0.0 is vulnerable to PHAR (PHP Archive) deserialization due to a lack of checking on the protocol before passing it into the file_get_contents() function. An attacker who can upload files of any type to the server can pass in the phar:// protocol to unserialize the uploaded file and instantiate arbitrary PHP objects. This can lead to remote code execution, especially when DOMPdf is used with frameworks with documented POP chains like Laravel or vulnerable developer code.

CVE-2021-3838 Affected Dompdf/dompdf Versions

1 component(s)
Fixed Versions:
2.0.0
Product / Package Ecosystem Affected Versions Fixed Version
dompdf/dompdf
 Packagist
< 2.0.0
2.0.0

References

NVD — CVE-2021-3838 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-3838
Security Fix Commit FIX COMMIT
https://github.com/dompdf/dompdf/commit/99aeec1efec9213e87098d42eb09439e7ee0bb6a
Dompdf/dompdf Source Repository REPOSITORY
https://github.com/dompdf/dompdf
huntr.com/bounties/0bdddc12-f... WEB
https://huntr.com/bounties/0bdddc12-ff67-4815-ab9f-6011a974f48e

Frequently Asked Questions

What is CVE-2021-3838?
CVE-2021-3838 is a security vulnerability in Dompdf/dompdf involving Deserialization of Untrusted Data in dompdf/dompdf under CWE-502: Deserialization of Untrusted Data.
Which Dompdf/dompdf versions are affected?
Affected versions include releases prior to 2.0.0 across affected packages: dompdf/dompdf.
What version fixes CVE-2021-3838?
Upgrading to 2.0.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is dompdf/dompdf affected?
Yes, dompdf/dompdf is affected in releases prior to 2.0.0. Upgrade your dependency to 2.0.0 or later.
What is the CVSS score of CVE-2021-3838?
CVE-2021-3838 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2021-3838?
CVE-2021-3838 is classified under CWE-502: Deserialization of Untrusted Data (The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.).
How can I check Packagist dependencies for CVE-2021-3838?
Run the dependency tree command: 'inspect dependencies for dompdf/dompdf'. 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-577p-7j7h-2jgf",
  "modified" : "2024-11-18T21:23:08Z",
  "published" : "2024-11-15T12:31:44Z",
  "aliases" : [ "CVE-2021-3838" ],
  "summary" : "Deserialization of Untrusted Data in dompdf/dompdf",
  "details" : "DomPDF before version 2.0.0 is vulnerable to PHAR (PHP Archive) deserialization due to a lack of checking on the protocol before passing it into the file_get_contents() function. An attacker who can upload files of any type to the server can pass in the phar:// protocol to unserialize the uploaded file and instantiate arbitrary PHP objects. This can lead to remote code execution, especially when DOMPdf is used with frameworks with documented POP chains like Laravel or vulnerable developer code.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "dompdf/dompdf"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.0.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-3838"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/dompdf/dompdf/commit/99aeec1efec9213e87098d42eb09439e7ee0bb6a"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/dompdf/dompdf"
  }, {
    "type" : "WEB",
    "url" : "https://huntr.com/bounties/0bdddc12-ff67-4815-ab9f-6011a974f48e"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-502" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-11-15T20:36:04Z",
    "nvd_published_at" : "2024-11-15T11:15:05Z"
  }
}