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CVE-2026-19873

HTML::FormFu versions through 2.08 for Perl allow resource exhaustion via an unbounded repeat count from the query string in Repeatable elements

7.5 HighFix available

HTML::FormFu versions through 2.08 for Perl allow resource exhaustion via an unbounded repeat count from the query string in Repeatable elements.

When a Repeatable element has counter_name set, its process method reads the repeat count from the named query string parameter, checks only that it is a positive integer, and passes it to repeat, which deep-clones the element's child subtree once per iteration. Nothing caps the value, and no attribute lets an application impose a limit.

The count is read on every request, before the form decides whether it was submitted, so a plain GET reaches the clone loop with no credentials, no session and no request body. Nesting multiplies: a Repeatable inside a Repeatable takes a counter at each level, so an outer and an inner value of 100 build 10,000 clones.

Once the form is submitted, each cloned field's constraints scan the whole element tree in _find_field_value, so cost grows faster than linearly with the count. A single request exhausts memory and CPU.

The latest release on CPAN is 2.07, from 2018. Version 2.08 exists only in the git repository.

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
None
Integrity
None
Availability
High

Exploit likelihood

0.52%Unchanged since Sep 1, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.5

HTML::FormFu versions through 2.08 for Perl allow resource exhaustion via an unbounded repeat count from the query string in Repeatable elements

HTML::FormFu versions through 2.08 for Perl allow resource exhaustion via an unbounded repeat count from the query string in Repeatable elements.

When a Repeatable element has counter_name set, its process method reads the repeat count from the named query string parameter, checks only that it is a positive integer, and passes it to repeat, which deep-clones the element's child subtree once per iteration. Nothing caps the value, and no attribute lets an application impose a limit.

The count is read on every request, before the form decides whether it was submitted, so a plain GET reaches the clone loop with no credentials, no session and no request body. Nesting multiplies: a Repeatable inside a Repeatable takes a counter at each level, so an outer and an inner value of 100 build 10,000 clones.

Once the form is submitted, each cloned field's constraints scan the whole element tree in _find_field_value, so cost grows faster than linearly with the count. A single request exhausts memory and CPU.

The latest release on CPAN is 2.07, from 2018. Version 2.08 exists only in the git repository.

Record
CVE-2026-19873
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-1284, CWE-770
Updated
2026-11-02
EUVDEUVD-2026-68458 7.5

HTML::FormFu versions through 2.08 for Perl allow resource exhaustion via an unbounded repeat count from the query string in Repeatable elements.

When a Repeatable element has counter_name set, its process method reads the repeat count from the named query string parameter, checks only that it is a positive integer, and passes it to repeat, which deep-clones the element's child subtree once per iteration. Nothing caps the value, and no attribute lets an application impose a limit.

The count is read on every request, before the form decides whether it was submitted, so a plain GET reaches the clone loop with no credentials, no session and no request body. Nesting multiplies: a Repeatable inside a Repeatable takes a counter at each level, so an outer and an inner value of 100 build 10,000 clones.

Once the form is submitted, each cloned field's constraints scan the whole element tree in _find_field_value, so cost grows faster than linearly with the count. A single request exhausts memory and CPU.

The latest release on CPAN is 2.07, from 2018. Version 2.08 exists only in the git repository.

Record
EUVD-2026-68458
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-8cjx-f34x-86x3 7.5

HTML::FormFu versions through 2.08 for Perl allow resource exhaustion via an unbounded repeat...

HTML::FormFu versions through 2.08 for Perl allow resource exhaustion via an unbounded repeat count from the query string in Repeatable elements.

When a Repeatable element has counter_name set, its process method reads the repeat count from the named query string parameter, checks only that it is a positive integer, and passes it to repeat, which deep-clones the element's child subtree once per iteration. Nothing caps the value, and no attribute lets an application impose a limit.

The count is read on every request, before the form decides whether it was submitted, so a plain GET reaches the clone loop with no credentials, no session and no request body. Nesting multiplies: a Repeatable inside a Repeatable takes a counter at each level, so an outer and an inner value of 100 build 10,000 clones.

Once the form is submitted, each cloned field's constraints scan the whole element tree in _find_field_value, so cost grows faster than linearly with the count. A single request exhausts memory and CPU.

The latest release on CPAN is 2.07, from 2018. Version 2.08 exists only in the git repository.

Record
GHSA-8cjx-f34x-86x3
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-770
Updated
2026-11-02
NVD 7.5

HTML::FormFu versions through 2.08 for Perl allow resource exhaustion via an unbounded repeat count from the query string in Repeatable elements.

When a Repeatable element has counter_name set, its process method reads the repeat count from the named query string parameter, checks only that it is a positive integer, and passes it to repeat, which deep-clones the element's child subtree once per iteration. Nothing caps the value, and no attribute lets an application impose a limit.

The count is read on every request, before the form decides whether it was submitted, so a plain GET reaches the clone loop with no credentials, no session and no request body. Nesting multiplies: a Repeatable inside a Repeatable takes a counter at each level, so an outer and an inner value of 100 build 10,000 clones.

Once the form is submitted, each cloned field's constraints scan the whole element tree in _find_field_value, so cost grows faster than linearly with the count. A single request exhausts memory and CPU.

The latest release on CPAN is 2.07, from 2018. Version 2.08 exists only in the git repository.

Record
CVE-2026-19873
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-770, CWE-1284
Updated
2026-11-02
OSVDEBIAN-CVE-2026-19873 7.5

HTML::FormFu versions through 2.08 for Perl allow resource exhaustion via an unbounded repeat count from the query string in Repeatable elements. When a Repeatable element has counter_name set, its process method reads the repeat count from the named query string parameter, checks only that it is a positive integer, and passes it to repeat, which deep-clones the element's child subtree once per iteration. Nothing caps the value, and no attribute lets an application impose a limit. The count is read on every request, before the form decides whether it was submitted, so a plain GET reaches the clone loop with no credentials, no session and no request body. Nesting multiplies: a Repeatable inside a Repeatable takes a counter at each level, so an outer and an inner value of 100 build 10,000 clones. Once the form is submitted, each cloned field's constraints scan the whole element tree in _find_field_value, so cost grows faster than linearly with the count. A single request exhausts memory and CPU. The latest release on CPAN is 2.07, from 2018. Version 2.08 exists only in the git repository.

Record
DEBIAN-CVE-2026-19873
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-19873 7.5

HTML::FormFu versions through 2.08 for Perl allow resource exhaustion via an unbounded repeat count from the query string in Repeatable elements. When a Repeatable element has counter_name set, its process method reads the repeat count from the named query string parameter, checks only that it is a positive integer, and passes it to repeat, which deep-clones the element's child subtree once per iteration. Nothing caps the value, and no attribute lets an application impose a limit. The count is read on every request, before the form decides whether it was submitted, so a plain GET reaches the clone loop with no credentials, no session and no request body. Nesting multiplies: a Repeatable inside a Repeatable takes a counter at each level, so an outer and an inner value of 100 build 10,000 clones. Once the form is submitted, each cloned field's constraints scan the whole element tree in _find_field_value, so cost grows faster than linearly with the count. A single request exhausts memory and CPU. The latest release on CPAN is 2.07, from 2018. Version 2.08 exists only in the git repository.

Record
UBUNTU-CVE-2026-19873
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVMGASA-2026-0404 No score

Updated perl-HTML-FormFu packages fix a security vulnerability

HTML::FormFu versions through 2.08 for Perl allow resource exhaustion via an unbounded repeat count from the query string in Repeatable elements. (CVE-2026-19873)

Record
MGASA-2026-0404
Updated
2026-11-02

Affected packages

Affected packages
PackageAffectedFixed
libhtml-formfu-perl
Debian:12
All versions, plus listed versions
2.07000-12.07000-22.07000-3
None known
libhtml-formfu-perl
Debian:13
All versions, plus listed versions
2.07000-22.07000-3
None known
libhtml-formfu-perl
Debian:14
before 2.07000-3, plus listed versions
2.07000-2
2.07000-3
perl-HTML-FormFu
Mageia:10
before 2.60.0-5.1.mga10
2.60.0-5.1.mga10
perl-HTML-FormFu
Mageia:9
before 2.60.0-4.1.mga9
2.60.0-4.1.mga9
libhtml-formfu-perl
Ubuntu:16.04:LTS
All versions, plus listed versions
2.01000-2
None known
libhtml-formfu-perl
Ubuntu:18.04:LTS
All versions, plus listed versions
2.05000-1
None known
libhtml-formfu-perl
Ubuntu:20.04:LTS
All versions, plus listed versions
2.07000-1
None known
libhtml-formfu-perl
Ubuntu:22.04:LTS
All versions, plus listed versions
2.07000-1
None known
libhtml-formfu-perl
Ubuntu:24.04:LTS
All versions, plus listed versions
2.07000-1
None known
libhtml-formfu-perl
Ubuntu:26.10
All versions, plus listed versions
2.07000-2
None known
libhtml-formfu-perl
Ubuntu:26.04:LTS
All versions, plus listed versions
2.07000-2
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-2026-19873 is a high vulnerability (CVSS 7.5) in libhtml-formfu-perl, published August 31, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.52%, the 44th percentile. Fixed in libhtml-formfu-perl 2.07000-3.

References

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