🛡️ CVE-2026-48821

🟡 CVSS 5.8 — Medium ✅ No Known Exploit CWE-79 NVD
5.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Shaarli is a personal bookmarking service. Versions 0.16.1 and prior contain a DOM-based Cross-Site Scripting (XSS) vulnerability in the Thumbnail Synchronizer feature. When an administrator runs the thumbnail update process, malicious bookmark titles are returned via an AJAX response and inserted into the DOM using innerHTML without proper sanitization. The issue originates from the interaction between the backend thumbnail update endpoint and the frontend JavaScript responsible for rendering update progress. On the backend, the ThumbnailsController::ajaxUpdate method returns bookmark data formatted using the 'raw' formatter. This includes the unescaped bookmark title in the JSON response. On the client side, the script thumbnails-update.js processes this AJAX response and dynamically updates the progress interface. Administrators using the thumbnail synchronization feature are affected and exploitation could lead to session hijacking, privilege escalation, backdoor injection and full compromise. This issue has been fixed in version 0.16.2.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs administrative privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability none.

Weakness class

CVE-2026-48821 is classified as CWE-79: Cross-site Scripting (XSS). User-supplied data is written into a page without escaping, so attacker script runs in the browser of anyone who views it.

Affected software

CVE-2026-48821 is recorded against 1 package.

  • unknown

Timeline and source

Published on 17 June 2026 and last revised on 23 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com
github.com
github.com

Details

Severity MEDIUM
CVSS Score 5.8
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N
CWE CWE-79
Public Exploit ✅ No
Source NVD
Published 2026-06-17
Updated 2026-08-11
Modified 2026-06-23
Fix URL N/A

Affected Packages

Software From version Fixed in
unknown — —

Similar Threats

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