CVE-2021-45394Public exploitNetwork attack vector

Server-side request forgery via unvalidated CSS link schemes

Published Jan 18, 2022 · Updated Aug 4, 2024

SSRF in Spipu HTML2PDF before 5.2.4 allows attackers to make server-side requests through crafted HTML link elements. The CSS parser passes each link href directly to PHP's file_get_contents, which accepts HTTP(S) and phar:// stream wrappers without scheme validation. An application must process attacker-controlled HTML; HTTP(S) yields blind SSRF, while phar:// on PHP 7 and earlier deserializes archive metadata and enables code execution when a gadget chain exists.

CVSS severity8.8
High
EPSS probability1.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in Spipu HTML2PDF before 5.2.4 allows attackers to make server-side requests through crafted HTML link elements. The CSS parser passes each link href directly to PHP's file_get_contents, which accepts HTTP(S) and phar:// stream wrappers without scheme validation. An application must process attacker-controlled HTML; HTTP(S) yields blind SSRF, while phar:// on PHP 7 and earlier deserializes archive metadata and enables code execution when a gadget chain exists.

The record

CVE
CVE-2021-45394
Published
Jan 18, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-918
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 18, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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-918Server-Side Request Forgery (SSRF)

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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