Bug 2536983

Summary:	CVE-2026-19873 perl-HTML-FormFu: HTML::FormFu: Denial of Service via unbounded repeat count in Repeatable elements [fedora-all]
Product:	[Fedora] Fedora	Reporter:	Vladimir Vasilev <vvasilev>
Component:	perl-HTML-FormFu	Assignee:	Emmanuel Seyman <emmanuel>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	high
Version:	rawhide	CC:	emmanuel, perl-devel
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["5fb6f2cf-40cc-48df-bb80-7fbfe4a8d42e"]}
Fixed In Version:	perl-HTML-FormFu-2.07-24.fc45 perl-HTML-FormFu-2.07-22.fc43 perl-HTML-FormFu-2.07-23.fc44	Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2026-09-29 00:15:21 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2526232

Description Vladimir Vasilev 2026-09-18 11:47:18 UTC

Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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.

Comment 1 Fedora Update System 2026-09-20 10:52:02 UTC

FEDORA-2026-18537daffc (perl-HTML-FormFu-2.07-23.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-18537daffc

Comment 2 Fedora Update System 2026-09-20 10:52:03 UTC

FEDORA-2026-219b6aef6c (perl-HTML-FormFu-2.07-22.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-219b6aef6c

Comment 3 Fedora Update System 2026-09-20 10:52:03 UTC

FEDORA-2026-94d32d2e8e (perl-HTML-FormFu-2.07-24.fc45) has been submitted as an update to Fedora 45.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-94d32d2e8e

Comment 4 Fedora Update System 2026-09-21 01:24:31 UTC

FEDORA-2026-219b6aef6c has been pushed to the Fedora 43 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-219b6aef6c`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-219b6aef6c

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 5 Fedora Update System 2026-09-21 01:36:03 UTC

FEDORA-2026-94d32d2e8e has been pushed to the Fedora 45 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-94d32d2e8e`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-94d32d2e8e

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 6 Fedora Update System 2026-09-21 01:55:33 UTC

FEDORA-2026-18537daffc has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-18537daffc`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-18537daffc

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 7 Fedora Update System 2026-09-29 00:15:21 UTC

FEDORA-2026-94d32d2e8e (perl-HTML-FormFu-2.07-24.fc45) has been pushed to the Fedora 45 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 8 Fedora Update System 2026-09-29 00:43:52 UTC

FEDORA-2026-219b6aef6c (perl-HTML-FormFu-2.07-22.fc43) has been pushed to the Fedora 43 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 9 Fedora Update System 2026-09-29 01:06:01 UTC

FEDORA-2026-18537daffc (perl-HTML-FormFu-2.07-23.fc44) has been pushed to the Fedora 44 stable repository.
If problem still persists, please make note of it in this bug report.