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CVE-2021-3902· NVD / CVE Program· CNA @huntr_ai

Improper Restriction of XML External Entity Reference in dompdf/dompdf

Noroxi assessment

Priority: Monitor (action score 39/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.95% (FIRST EPSS); higher than 60.9% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: php-dompdf (Debian:12) 2.0.2+dfsg-1; dompdf/dompdf (Packagist) 2.0.0.

Low priority for now. Upgrade to php-dompdf (Debian:12) 2.0.2+dfsg-1; dompdf/dompdf (Packagist) 2.0.0 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

An improper restriction of external entities (XXE) vulnerability in dompdf/dompdf's SVG parser allows for Server-Side Request Forgery (SSRF) and deserialization attacks. This issue affects all versions prior to 2.0.0. The vulnerability can be exploited even if the isRemoteEnabled option is set to false. It allows attackers to perform SSRF, disclose internal image files, and cause PHAR deserialization attacks.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Nov 15, 2024
Updated
Jun 17, 2026
EPSS
0.9% · 60th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.9%

CISA SSVC decision

Exploitation
proof of concept
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
9.8
CNA · @huntr_ai
9.8
agree

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-3902

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
dompdf projectdompdf

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • dompdf project dompdfbefore 2.0.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (@huntr_ai). Independent of NVD's CPE analysis and usually ahead of it.

  • dompdf dompdf/dompdf

    • unspecified and later · before 2.0.0affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12php-dompdfbefore 2.0.2+dfsg-12.0.2+dfsg-1
Packagistdompdf/dompdfbefore 2.0.02.0.0

Same product

dompdf project: all records

Other highest-scoring records for the same primary product.

  • CVE-2022-28368Dompdf 1.2.1 allows remote code execution via a .php file in the src:url field of an @font-face Cascading Style Sheets (CSS) statement (with
    64This week
  • CVE-2023-24813URI validation failure on SVG parsing. Bypass of CVE-2023-23924
    40Plan
  • CVE-2023-23924URI validation failure on SVG parsing in Dompdf
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2023-50262Dec 13, 2023 · Dompdf possible DoS caused by infinite recursion when parsing SVG images
    30Monitor
  • ← EarlierCVE-2021-3838Nov 15, 2024 · PHAR Deserialization in dompdf/dompdf
    39Monitor
  • Later →CVE-2026-55554Jul 28, 2026 · Dompdf: Chroot Validation Bypass
    9Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:php-dompdf2.0.2+dfsg-1 · Debian:12Package registry (OSV)
Packagist:dompdf/dompdf2.0.0Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-611 · Improper Restriction of XML External Entity Reference

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records