CVE-2026-54565

What it is

rhwp is an HWP viewer and editor implemented in Rust and WebAssembly. Prior to rhwp 0.7.15 and rhwp Chrome and Firefox extension 0.2.4, the browser extensions use an all-URLs host permission to detect HWP and HWPX links on visited pages, but the service workers do not validate message senders, URL schemes, or destination addresses before privileged fetches. The affected paths are rhwp-chrome/manifest.json, rhwp-chrome/content-script.js, rhwp-chrome/sw/message-router.js, rhwp-chrome/sw/thumbnail-extractor.js, rhwp-firefox/manifest.json, rhwp-firefox/content-script.js, rhwp-firefox/sw/message-router.js, and rhwp-firefox/sw/thumbnail-extractor.js. An untrusted page can make the fetch-file and extract-thumbnail handlers request localhost or private-network resources. When a target HWP or HWPX file contains an extractable PrvImage, the extension returns the preview as a data URI in page-readable DOM, allowing page script to read it. The flaw also permits internal-resource existence and port probing and extension presence or version fingerprinting. Exploitation requires a user to visit an untrusted page while the extension is enabled, and preview disclosure is limited to an extractable PrvImage. This issue is fixed in rhwp 0.7.15 and rhwp Chrome and Firefox extension 0.2.4.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. Limited direct impact.

Exploit odds

0.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-17 21:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-09-24 21:25 UTC Last updatedMost recent change to the record

Details

Published

2026-09-17 21:17 UTC

Last modified

2026-09-24 21:25 UTC

Exploit probability

0.2% · EPSS, next 30 days

Weakness

CWE-200 · Information exposure

Record status

Deferred

Attack profile CVSS 3.1 · 4.7

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

None

Availability

None