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Shaarli CVE-2026-48822

MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-06-17 GitHub_M
5.8
CVSS 3.1 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
5.8 MEDIUM
AV:L/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N
vuln.today AI
8.1 HIGH

Network-accessible web application warrants AV:N over AV:L; S:C applies as injected script executes in victim's browser; PR:H reflects Shaarli's default single-owner bookmark creation model.

3.1 AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:N
4.0 AV:N/AC:L/AT:N/PR:H/UI:A/VC:L/VI:L/VA:N/SC:H/SI:H/SA:N

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N
Attack Vector
Local
Attack Complexity
Low
Privileges Required
High
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Lifecycle Timeline

2
Source Code Evidence Fetched
Jun 17, 2026 - 20:34 vuln.today
Analysis Generated
Jun 17, 2026 - 20:34 vuln.today

DescriptionCVE.org

Shaarli is a personal bookmarking service. Versions 0.16.1 and prior contain a stored Cross-Site Scripting (XSS) vulnerability in the Markdown-to-HTML conversion process used in the Bookmark Description field. An authenticated user can inject a malicious javascript: URI inside a Markdown link. The vulnerability originates in the filterProtocols method within BookmarkMarkdownFormatter.php.This method attempts to sanitize Markdown links by filtering dangerous protocols (such as javascript:) before rendering. It uses the following regular expression: (#]\((.*?)\)#is). This regex is designed to detect inline Markdown links, but it fails to detect Markdown reference-style links because reference-style links are resolved by the Markdown parser after preprocessing. The filterProtocols method never inspects the actual URL used in these references and as a result, an attacker can supply a javascript: URI inside a reference definition. This issue has been fixed in version 0.16.2.

AnalysisAI

Stored XSS in Shaarli's Markdown rendering pipeline (versions 0.16.1 and prior) allows an authenticated user to inject malicious javascript: URIs via Markdown reference-style links in bookmark descriptions, bypassing the filterProtocols sanitization method in BookmarkMarkdownFormatter.php. When any user or guest visitor views the crafted bookmark, arbitrary JavaScript executes in their browser context, enabling session theft or unauthorized actions. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Recon
Authenticate as Shaarli admin or compromise admin account
Delivery
Craft bookmark description using Markdown reference-style javascript: URI syntax
Exploit
Submit bookmark to persistent storage
Install
Victim loads bookmark listing or detail page
C2
Markdown parser resolves reference link, bypassing sanitization
Execute
Injected JavaScript executes in victim browser
Impact
Steal session token or perform actions as victim

Vulnerability AssessmentAI

Exploitation Exploitation requires an authenticated session with bookmark creation privileges on the target Shaarli instance - consistent with PR:H in the CVSS vector, reflecting Shaarli's default single-owner design where only the instance administrator can create bookmarks. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The NVD-assigned CVSS base score of 5.8 uses the vector CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker authenticated as a Shaarli administrator creates a bookmark whose description contains a Markdown reference-style link - for example, [click here][ref] paired with a separate line [ref]: javascript:alert(document.cookie) - which passes through the filterProtocols sanitization undetected. When any user or unauthenticated guest loads the bookmark listing or detail page, the Markdown parser resolves the reference and renders a javascript: anchor that executes in the viewer's browser, delivering the attacker's payload. …
Remediation Upgrade to Shaarli v0.16.2, released 2026-05-23, which patches the filterProtocols method to handle Markdown reference-style link definitions and also addresses two additional XSS vectors: encoding of tag text in Awesomplete autocomplete suggestions and sanitization of thumbnail update DOM insertions (see https://github.com/shaarli/Shaarli/releases/tag/v0.16.2 and advisory GHSA-2hgr-63wv-x462). … Detailed patch versions, workarounds, and compensating controls in full report.

Threat intelligence, references, and detailed analysis are available after sign-in.

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CVE-2026-48822 vulnerability details – vuln.today

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