CVE-2026-66843Network attack vector

Document embedding via incomplete object URI filtering

Published Aug 6, 2026 · Updated Aug 6, 2026

Content injection in René Föhring html_sanitize_ex 0.3.1 through 1.4.4 and 1.5.0-rc.0 through 1.5.2 allows remote attackers to embed documents. The HTML5 scrubber's object attribute handler checks only a lowercase javascript: prefix instead of applying URI-scheme filtering, leaving mixed-case schemes, data URIs, protocol-relative URLs, and same-origin paths intact. Exposure requires HtmlSanitizeEx.html5/1 or an HTML5-derived scrubber and sanitized output rendered to other users; host-origin script execution also requires attacker-controlled same-origin HTML.

CVSS severity2.3
Low
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Content injection in René Föhring html_sanitize_ex 0.3.1 through 1.4.4 and 1.5.0-rc.0 through 1.5.2 allows remote attackers to embed documents. The HTML5 scrubber's object attribute handler checks only a lowercase javascript: prefix instead of applying URI-scheme filtering, leaving mixed-case schemes, data URIs, protocol-relative URLs, and same-origin paths intact. Exposure requires HtmlSanitizeEx.html5/1 or an HTML5-derived scrubber and sanitized output rendered to other users; host-origin script execution also requires attacker-controlled same-origin HTML.

The record

CVE
CVE-2026-66843
Published
Aug 6, 2026
Updated
Aug 6, 2026
Vendor
René Föhring
Product
html_sanitize_ex
Classifications
CWE-829, CAPEC-175, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 6, 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=0.3.1 <1.5.3
  2. Affected versionversion=8976d64ea0b77d26093a94a43ec48a3978e8d028 <bec27fec4de99e40c68c4285a610e09e791a3eaf

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

René Föhring · html_sanitize_exversion=0.3.1 <1.5.3; version=8976d64ea0b77d26093a94a43ec48a3978e8d028 <bec27fec4de99e40c68c4285a610e09e791a3eaf

Published CVSS scores

2.3Erlang Ecosystem FoundationCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA: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 exploitUnconfirmed

Weakness, pattern, technique

CWE-829Inclusion of Functionality from Untrusted Control Sphere
CAPEC-175Code Inclusion
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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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