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CVE-2025-55166

svg-sanitizer By-Passing Attribute Sanitization

5.1 MediumFix available

savg-sanitizer is a PHP SVG/XML sanitizer. Prior to version 0.22.0, the sanitization logic in the cleanXlinkHrefs method only searches for lower-case attribute name, which allows to by-pass the isHrefSafeValue check. As a result this allows cross-site scripting or linking to external domains. This issue has been patched in version 0.22.0.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Active

What an attacker can affect

Confidentiality
Low
Integrity
Low
Availability
None

Exploit likelihood

0.54%Up 0.5 points since Aug 13, 2025
90%50%10%1%

What each source reports

CVE List Score used 5.1

svg-sanitizer By-Passing Attribute Sanitization

savg-sanitizer is a PHP SVG/XML sanitizer. Prior to version 0.22.0, the sanitization logic in the cleanXlinkHrefs method only searches for lower-case attribute name, which allows to by-pass the isHrefSafeValue check. As a result this allows cross-site scripting or linking to external domains. This issue has been patched in version 0.22.0.

Record
CVE-2025-55166
CVSS 4.0
5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-79, CWE-601
Updated
2026-11-02
EUVDEUVD-2025-24263 5.1

savg-sanitizer is a PHP SVG/XML sanitizer. Prior to version 0.22.0, the sanitization logic in the cleanXlinkHrefs method only searches for lower-case attribute name, which allows to by-pass the isHrefSafeValue check. As a result this allows cross-site scripting or linking to external domains. This issue has been patched in version 0.22.0.

Record
EUVD-2025-24263
CVSS 4.0
5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-22wq-q86m-83fh 5.1

svg-sanitizer Bypasses Attribute Sanitization

Problem

The sanitization logic at https://github.com/darylldoyle/svg-sanitizer/blob/0.21.0/src/Sanitizer.php#L454-L481 only searches for lower-case attribute names (e.g. xlink:href instead of xlink:HrEf), which allows to by-pass the isHrefSafeValue check. As a result this allows cross-site scripting or linking to external domains.

Proof-of-concept

provided by azizk

<?xml version="1.0" encoding="UTF-8"?>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="100" height="100">
  <a xlink:hReF="javascript:alert(document.domain)">
    <rect width="100" height="50" fill="red"></rect>
    <text x="50" y="30" text-anchor="middle" fill="white">Click me</text>
  </a>
</svg>

Credits

The mentioned findings and proof-of-concept example were reported to the TYPO3 Security Team by the external security researcher azizk <[email protected]>.

Record
GHSA-22wq-q86m-83fh
CVSS 4.0
5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-79, CWE-601
Updated
2026-11-02
NVD 5.1

savg-sanitizer is a PHP SVG/XML sanitizer. Prior to version 0.22.0, the sanitization logic in the cleanXlinkHrefs method only searches for lower-case attribute name, which allows to by-pass the isHrefSafeValue check. As a result this allows cross-site scripting or linking to external domains. This issue has been patched in version 0.22.0.

Record
CVE-2025-55166
CVSS 4.0
5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-79, CWE-601
Updated
2026-11-02
OSV 5.1

svg-sanitizer By-Passing Attribute Sanitization

savg-sanitizer is a PHP SVG/XML sanitizer. Prior to version 0.22.0, the sanitization logic in the cleanXlinkHrefs method only searches for lower-case attribute name, which allows to by-pass the isHrefSafeValue check. As a result this allows cross-site scripting or linking to external domains. This issue has been patched in version 0.22.0.

Record
CVE-2025-55166
CVSS 4.0
5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-601, CWE-79
Updated
2026-11-02
OSVGHSA-22wq-q86m-83fh 5.1

svg-sanitizer Bypasses Attribute Sanitization

Problem

The sanitization logic at https://github.com/darylldoyle/svg-sanitizer/blob/0.21.0/src/Sanitizer.php#L454-L481 only searches for lower-case attribute names (e.g. xlink:href instead of xlink:HrEf), which allows to by-pass the isHrefSafeValue check. As a result this allows cross-site scripting or linking to external domains.

Proof-of-concept

provided by azizk

<?xml version="1.0" encoding="UTF-8"?>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="100" height="100">
  <a xlink:hReF="javascript:alert(document.domain)">
    <rect width="100" height="50" fill="red"></rect>
    <text x="50" y="30" text-anchor="middle" fill="white">Click me</text>
  </a>
</svg>

Credits

The mentioned findings and proof-of-concept example were reported to the TYPO3 Security Team by the external security researcher azizk <[email protected]>.

Record
GHSA-22wq-q86m-83fh
CVSS 4.0
5.1 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-601, CWE-79
Updated
2026-11-02
OSVCLSA-2026-1787820940 No score

TuxCare security update for enshrined/svg-sanitize (1 CVE)

TuxCare rebuilt enshrined/svg-sanitize to address 1 CVE. Fixed in 0.16.0-p1+tuxcare.

Record
CLSA-2026-1787820940
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
enshrined/svg-sanitize
Packagist
 before 0.22.0
0.22.0
enshrined/svg-sanitize
TuxCare:Packagist
 0.16.0 up to 0.16.0-p1+tuxcare
0.16.0-p1+tuxcare
enshrined/svg-sanitize
Packagist
 before 0.22.0, plus listed versions
0.1.00.1.10.1.20.1.30.1.4
Show 42 moreShow less
0.1.50.1.60.10.00.11.00.12.00.13.00.13.10.13.20.13.30.14.00.14.10.15.00.15.10.15.20.15.30.15.40.16.00.17.00.18.00.19.00.2.00.2.10.20.00.21.00.3.00.4.00.4.10.5.00.5.10.5.20.5.30.5.3.10.6.00.7.00.7.10.7.20.8.00.8.10.8.20.9.00.9.10.9.2
0.22.0

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-55166 is a medium vulnerability (CVSS 5.1) in Darylldoyle Svg-sanitizer, published August 12, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.54%, the 45th percentile. Fixed in enshrined/svg-sanitize 0.22.0.

References

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