# CVE-2026-111946: Plack::Middleware::ETag inode disclosure in default ETag header

Source: https://junglewise.ai/threats/cve-2026-111946-plack-middleware-etag-versions-from-0-04-before-0-06-for-perl  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-19. Updated: 2026-10-19  
License: CC BY 4.0 with a link back

CVE-2026-111946 · Severity: info · Published 2026-10-19

Plack::Middleware::ETag is a Perl module that adds caching headers to web responses. Versions 0.04 through 0.05 leak internal filesystem inode numbers in ETag headers when serving files, allowing attackers to correlate files across different URLs and aid backend fingerprinting attacks.

Vendors: [CPAN](https://junglewise.ai/threats/vendors/cpan).

## Quick answers

**Is CVE-2026-111946 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-111946 being exploited in the wild.

**How severe is CVE-2026-111946?** Informational severity, published 19 October 2026.

**Which products and versions are affected?** CPAN Plack::Middleware::ETag 0.04-0.05.

**Is there a fix for CVE-2026-111946?** Yes: fixed in 0.06. Until then: Set the file_etag option explicitly to prevent inode inclusion in the ETag header, or upgrade to version 0.06 or later where this is the default behavior. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-111946 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-111946?** Check whether you run CPAN Plack::Middleware::ETag at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 0.06

Set the file_etag option explicitly to prevent inode inclusion in the ETag header, or upgrade to version 0.06 or later where this is the default behavior.

## Technical details

The ETag generation logic includes the file's inode number, modification time, and size when the response body is a filehandle and the file_etag option is not explicitly configured. An attacker can extract inode numbers from HTTP response headers to map the filesystem structure and correlate files served from different URLs, similar to CVE-2003-1418 in Apache.

## Affected products

- CPAN Plack::Middleware::ETag 0.04-0.05

## Timeline

- 2026-10-18: disclosed
- 2026-10-19: advisory

## References

- [https://cpan.org/modules](https://cpan.org/modules)
- [https://github.com/robrwo/perl-Plack-Middleware-ETag/security/advisories/GHSA-943g-rgq5-6xc8](https://github.com/robrwo/perl-Plack-Middleware-ETag/security/advisories/GHSA-943g-rgq5-6xc8)