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7.5
CVE-2026-19873: HTML::FormFu can be overloaded by crafted URL
CVE-2026-19873 · published 2 months ago
Summary
Versions of HTML::FormFu up to 2.08, as shipped in Debian and Canonical packages, accept a repeat count from the query string without any limit. An attacker can send a specially crafted request that forces the form to create many duplicate fields, quickly using up memory and CPU and potentially crashing the server. Upgrade to a version that enforces a maximum count or add your own checks to restrict the repeat parameter.
What to do
- Update debian libhtml-formfu-perl to version 2.07000-3.
Affected software
| Ecosystem | Vendor | Product | Affected versions |
|---|---|---|---|
| Debian:14 | debian | libhtml-formfu-perl |
< 2.07000-3 Fix: upgrade to 2.07000-3
|
| Debian:11 | debian | libhtml-formfu-perl | All versions |
| Debian:12 | debian | libhtml-formfu-perl | All versions |
| Debian:13 | debian | libhtml-formfu-perl | All versions |
| Ubuntu:16.04:LTS | canonical | libhtml-formfu-perl | All versions |
Original advisory text
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...
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.
References
- https://security-tracker.debian.org/tracker/CVE-2026-19873 Vendor Advisory
- http://www.openwall.com/lists/oss-security/2026/08/31/7
- https://github.com/FormFu/HTML-FormFu/issues/71 Third Party Advisory
- https://security.metacpan.org/patches/H/HTML-FormFu/2.08/CVE-2026-19873-r1.patch Third Party Advisory
- http://www.openwall.com/lists/oss-security/2026/09/01/1
- https://ubuntu.com/security/CVE-2026-19873 Third Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2026-19873 Third Party Advisory
- https://lists.security.metacpan.org/cve-announce/msg/43141785/ Third Party Advisory
Internet-facing
14 days
Internal
60 days
- Not known to be exploited
- Can be exploited automatically
- Gives an attacker partial control
Severity
7.5
High
Type
CWE-770Allocation of Resources Without Limits
CWE-1284Improper Validation of Specified Quantity in Input
Timeline
Published31 Aug 2026
Updated4 Nov 2026
First seen31 Aug 2026
Sources
CVE-2026-19873 · NVD
CVE-2026-19873 · MITRE
DEBIAN-CVE-2026-19873 · OSV
UBUNTU-CVE-2026-19873 · OSV
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