Security Digest · Vulnerability record
CVE-2021-3838: Deserialization of Untrusted Data in dompdf/dompdf
DomPDF before version 2.0.0 is vulnerable to PHAR deserialization due to a lack of checking on the protocol before passing it into the filegetcontents() function.
CVSS 9.8 Critical EPSS 1.4% · p73
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 1.4%, percentile 73: FIRST’s model estimates a 1.4% chance of exploitation activity in the next 30 days, higher than 73% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
dompdf/dompdf(Composer (PHP)) < 2.0.0, fixed in 2.0.0. Check your lockfile, including transitive dependencies.
What it is
DomPDF before version 2.0.0 is vulnerable to PHAR deserialization due to a lack of checking on the protocol before passing it into the filegetcontents() 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.
From the GitHub advisory
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 filegetcontents() 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.
Weakness type: CWE-502.
Product: dompdf/dompdf (Composer (PHP)) · Assigned by: @huntr_ai · Published: 2024-11-15
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| Composer (PHP) | dompdf/dompdf | < 2.0.0 | 2.0.0 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| dompdf | dompdf/dompdf | unspecified < 2.0.0 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| @huntr_ai | 3.0 | 9.8 Critical | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CISA-ADP | 3.1 | 9.8 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 1.43% probability of exploitation activity in the next 30 days; percentile 73.
Timeline
- — CVE record published by @huntr_ai
- — GitHub-reviewed advisory GHSA-577p-7j7h-2jgf published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-577p-7j7h-2jgf github.com
- CVE.org record CVE-2021-3838 cve.org
- NVD entry CVE-2021-3838 nvd.nist.gov
Other references from the CVE record and advisory
- huntr.com huntr.com
- github.com github.com
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