poppler: Denial of Service in pdfseparate utility (infinite recursion) (CVE-2025-50420) #shorts

Summary

Today’s episode covers CVE-2025-50420, an important denial of service vulnerability discovered in the pdfseparate utility of freedesktop’s Poppler library version 25.04.0. Attackers can exploit this issue by providing a specially crafted PDF file that triggers infinite recursion, exhausting system resources and crashing the utility. SUSE has already released advisories and patches to address this flaw.

Product details

Poppler is an open-source PDF rendering library maintained by freedesktop and widely used in Linux distributions. The pdfseparate command-line tool, included in Poppler version 25.04.0, extracts individual pages from multi-page PDF documents. SUSE has issued a security advisory and released an updated package fixing this issue for all supported SUSE Enterprise Linux and openSUSE releases.

Vulnerability type summary

CVE-2025-50420 is classified as a denial of service vulnerability. The underlying flaw is infinite recursion: malformed PDF structures cause the pdfseparate function to repeatedly call itself without a terminating condition. The result is unbounded stack or memory growth that leads to crashes or hangs.

Details of the vulnerability

A crafted PDF can embed circular object references that pdfseparate follows recursively. Because the code lacks sufficient recursion limits or cycle detection, the parser consumes all available stack frames or heap memory. Remote or local attackers who can feed such a file into pdfseparate will cause the utility to abort or hang, disrupting dependent workflows.

Conclusion

To protect your systems, apply the SUSE updates or upgrade Poppler to a version that includes the infinite recursion safeguard. Other distributions should verify their Poppler packages and patch accordingly. Regularly reviewing PDF processing tools for updated security advisories will help prevent similar denial of service risks in the future.

Watch the full video on YouTube: CVE-2025-50420

Remediation and exploitation details

This chain involves the following actors

  • Malicious User: Initiator of denial of service attack

This following systems are involved

  • poppler v25.04.0 pdfseparate utility (Extract individual pages from PDF files): Target of the infinite recursion vulnerability

Attack entry point

  • Crafted PDF file: A specially constructed document containing cyclic object references designed to trigger unbounded recursion in the pdfseparate parser

Remediation actions

System Administrator
Apply the SUSE security advisory that patches the infinite recursion issue
poppler v25.04.0 pdfseparate utility
System Administrator
Upgrade the poppler package to the fixed version released after 2025-08-04
poppler pdfseparate utility

Exploitation actions

Design a PDF object graph where objects reference each other in a loop

Malicious User
Create a PDF file with recursive object references
poppler v25.04.0 pdfseparate utility
Examples:
  • Object 10 references Object 11, Object 11 references Object 10

Run the utility with the malicious PDF as input

Malicious User
Invoke the pdfseparate command on the crafted file
poppler v25.04.0 pdfseparate utility
Examples:
  • pdfseparate malicious.pdf page-%d.pdf

Unbounded recursive parsing of nested objects

poppler pdfseparate utility
Parse the PDF structure and follow the cyclic references
poppler v25.04.0 pdfseparate utility
Examples:

Infinite recursion leading to resource exhaustion

poppler pdfseparate utility
Consume stack and memory indefinitely until the process or host fails
poppler v25.04.0 pdfseparate utility
Examples:

Related Content

NOTE: The following related content has not been vetted and may be unsafe.

CVE database technical details

CVE ID
CVE-2025-50420
Description
An issue in the pdfseparate utility of freedesktop poppler v25.04.0 allows attackers to cause an infinite recursion via supplying a crafted PDF file. This can lead to a Denial of Service (DoS).
Provider
mitre
CWE / problem types
n/a
Affected Software Versions
n/a:n/a:[{'version': 'n/a', 'status': 'affected'}]
Date Published
2025-08-04T00:00:00.000Z
Last Updated
2025-08-05T16:47:17.021Z