CVE-2026-55555Public exploitNetwork attack vector

File existence disclosure via unvalidated font URLs

Published Jul 28, 2026 · Updated Jul 28, 2026

Observable discrepancy in dompdf before 3.1.6 allows remote attackers to determine whether local server files exist via crafted HTML. Stylesheet::resolve_url processes repeated file URLs from CSS @font-face rules without applying configured protocol and path checks, so existing paths exhaust memory while missing paths return quickly. Exploitation requires unrestricted or unsanitized HTML, large requests, and a reachable PHP memory limit; it reveals file existence, not file contents.

CVSS severity6.3
Medium
EPSS probability0.35%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Observable discrepancy in dompdf before 3.1.6 allows remote attackers to determine whether local server files exist via crafted HTML. Stylesheet::resolve_url processes repeated file URLs from CSS @font-face rules without applying configured protocol and path checks, so existing paths exhaust memory while missing paths return quickly. Exploitation requires unrestricted or unsanitized HTML, large requests, and a reachable PHP memory limit; it reveals file existence, not file contents.

The record

CVE
CVE-2026-55555
Published
Jul 28, 2026
Updated
Jul 28, 2026
Vendor
dompdf
Product
dompdf
Classifications
CWE-203, T1083
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 28, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.1.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

dompdf · dompdfversion=< 3.1.6

Published CVSS scores

6.3GitHubCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
7.5NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-203Observable Discrepancy
T1083File and Directory Discovery

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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