CVE-2026-48821
Shaarli: DOM-based Cross-Site Scripting (XSS) in Thumbnail Synchronizer
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.
INFO
Published Date :
June 17, 2026, 9:16 p.m.
Last Modified :
June 23, 2026, 3:44 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Shaarli to version 0.16.2 or later.
- Avoid using the thumbnail synchronization feature.
- Review and sanitize user-generated content.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-48821.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-48821 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-48821
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-48821 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-48821 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 18, 2026
Action Type Old Value New Value Added Reference https://github.com/shaarli/Shaarli/security/advisories/GHSA-mw63-f9qj-c5h3 Added SSVC {'id': 'CVE-2026-48821', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-18T12:56:58.369827Z'} -
New CVE Received by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'shaarli', 'product': 'Shaarli', 'versions': [{'status': 'affected', 'version': '< 0.16.2'}]}] Added 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. Added CVSS V3.1 AV:L/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N Added CWE CWE-79 Added Reference https://github.com/shaarli/Shaarli/releases/tag/v0.16.2 Added Reference https://github.com/shaarli/Shaarli/security/advisories/GHSA-mw63-f9qj-c5h3