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CVE-2025-15646

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion

9.8 CriticalFix available

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion.

Support for the <template> element was added to libgumbo 0.10.0 in 2015, but the walk_tree function in lib/HTML/Gumbo.xs was not updated to support it. The element was treated as a text-node, where strlen() over-reads the heap block that the pointer addresses.

Any caller that runs parse() with the default format => 'string', or with format => 'tree', on input containing a <template> element serializes the over-read bytes into the returned result, disclosing bounded heap contents. format => 'callback' reaches a croak on the unhandled node type and is unaffected.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.67%Unchanged since Jul 2, 2026
90%50%10%1%

What each source reports

CVE List Score used 9.8

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion.

Support for the <template> element was added to libgumbo 0.10.0 in 2015, but the walk_tree function in lib/HTML/Gumbo.xs was not updated to support it. The element was treated as a text-node, where strlen() over-reads the heap block that the pointer addresses.

Any caller that runs parse() with the default format => 'string', or with format => 'tree', on input containing a <template> element serializes the over-read bytes into the returned result, disclosing bounded heap contents. format => 'callback' reaches a croak on the unhandled node type and is unaffected.

Record
CVE-2025-15646
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-843, CWE-125
Updated
2026-11-02
EUVDEUVD-2025-210396 9.8

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion.

Support for the <template> element was added to libgumbo 0.10.0 in 2015, but the walk_tree function in lib/HTML/Gumbo.xs was not updated to support it. The element was treated as a text-node, where strlen() over-reads the heap block that the pointer addresses.

Any caller that runs parse() with the default format => 'string', or with format => 'tree', on input containing a <template> element serializes the over-read bytes into the returned result, disclosing bounded heap contents. format => 'callback' reaches a croak on the unhandled node type and is unaffected.

Record
EUVD-2025-210396
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-754r-h5mg-r795 9.8

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion. Support for...

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion.

Support for the <template> element was added to libgumbo 0.10.0 in 2015, but the walk_tree function in lib/HTML/Gumbo.xs was not updated to support it. The element was treated as a text-node, where strlen() over-reads the heap block that the pointer addresses.

Any caller that runs parse() with the default format => 'string', or with format => 'tree', on input containing a <template> element serializes the over-read bytes into the returned result, disclosing bounded heap contents. format => 'callback' reaches a croak on the unhandled node type and is unaffected.

Record
GHSA-754r-h5mg-r795
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-125
Updated
2026-11-02
NVD 9.8

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion.

Support for the <template> element was added to libgumbo 0.10.0 in 2015, but the walk_tree function in lib/HTML/Gumbo.xs was not updated to support it. The element was treated as a text-node, where strlen() over-reads the heap block that the pointer addresses.

Any caller that runs parse() with the default format => 'string', or with format => 'tree', on input containing a <template> element serializes the over-read bytes into the returned result, disclosing bounded heap contents. format => 'callback' reaches a croak on the unhandled node type and is unaffected.

Record
CVE-2025-15646
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-125, CWE-843
Updated
2026-11-02
OSV 9.8

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion.

Support for the <template> element was added to libgumbo 0.10.0 in 2015, but the walk_tree function in lib/HTML/Gumbo.xs was not updated to support it. The element was treated as a text-node, where strlen() over-reads the heap block that the pointer addresses.

Any caller that runs parse() with the default format => 'string', or with format => 'tree', on input containing a <template> element serializes the over-read bytes into the returned result, disclosing bounded heap contents. format => 'callback' reaches a croak on the unhandled node type and is unaffected.

Record
CVE-2025-15646
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-125, CWE-843
Updated
2026-11-02
OSVDEBIAN-CVE-2025-15646 9.8

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion. Support for the <template> element was added to libgumbo 0.10.0 in 2015, but the walk_tree function in lib/HTML/Gumbo.xs was not updated to support it. The element was treated as a text-node, where strlen() over-reads the heap block that the pointer addresses. Any caller that runs parse() with the default format => 'string', or with format => 'tree', on input containing a <template> element serializes the over-read bytes into the returned result, disclosing bounded heap contents. format => 'callback' reaches a croak on the unhandled node type and is unaffected.

Record
DEBIAN-CVE-2025-15646
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2025-15646 9.8

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion. Support for the <template> element was added to libgumbo 0.10.0 in 2015, but the walk_tree function in lib/HTML/Gumbo.xs was not updated to support it. The element was treated as a text-node, where strlen() over-reads the heap block that the pointer addresses. Any caller that runs parse() with the default format => 'string', or with format => 'tree', on input containing a <template> element serializes the over-read bytes into the returned result, disclosing bounded heap contents. format => 'callback' reaches a croak on the unhandled node type and is unaffected.

Record
UBUNTU-CVE-2025-15646
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
libhtml-gumbo-perl
Debian:12
before 0.18-3+deb12u1, plus listed versions
0.18-3
0.18-3+deb12u1
libhtml-gumbo-perl
Debian:13
before 0.18-5
0.18-5
libhtml-gumbo-perl
Debian:14
before 0.18-5
0.18-5
libhtml-gumbo-perl
Ubuntu:18.04:LTS
All versions, plus listed versions
0.17-1build1
None known
libhtml-gumbo-perl
Ubuntu:20.04:LTS
All versions, plus listed versions
0.18-2build10.18-2build2
None known
libhtml-gumbo-perl
Ubuntu:22.04:LTS
All versions, plus listed versions
0.18-2build30.18-2build4
None known
libhtml-gumbo-perl
Ubuntu:24.04:LTS
All versions, plus listed versions
0.18-3build10.18-3build20.18-3build30.18-3build40.18-3build5
None known

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-2025-15646 is a critical vulnerability (CVSS 9.8) in Bps Html::gumbo, published July 1, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.67%, the 52nd percentile. Fixed in libhtml-gumbo-perl 0.18-3+deb12u1.

References

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