CVE-2026-33436Public exploitNetwork attack vector

Reflected XSS via unsanitized uploaded filenames

Published Apr 17, 2026 · Updated Apr 17, 2026

Reflected XSS in Stirling PDF before 2.0.0 allows remote attackers to execute JavaScript by inducing a user to upload a crafted file. Upload interfaces place the user-controlled filename into HTML with innerHTML without encoding or sanitizing special characters. Exploitation requires the targeted user to upload the attacker-crafted file; the script then runs only in that user’s active browser session and can read browser-visible data.

CVSS severity3.1
Low
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in Stirling PDF before 2.0.0 allows remote attackers to execute JavaScript by inducing a user to upload a crafted file. Upload interfaces place the user-controlled filename into HTML with innerHTML without encoding or sanitizing special characters. Exploitation requires the targeted user to upload the attacker-crafted file; the script then runs only in that user’s active browser session and can read browser-visible data.

The record

CVE
CVE-2026-33436
Published
Apr 17, 2026
Updated
Apr 17, 2026
Vendor
Stirling PDF
Product
Stirling PDF
Classifications
CWE-116, CWE-20, CWE-79, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=< 2.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Stirling PDF · Stirling PDFversion=< 2.0.0

Published CVSS scores

3.1GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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-116Improper Encoding or Escaping of Output
CWE-20Improper Input Validation
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1204.002User Execution: Malicious File

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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