Shaarli vulnerable to stored XSS via raw bookmark title in document <title> element on public permalink page

published 2026-08-20 2 mo ago modified 2026-10-26 14 d ago also EUVD-2026-63551

cvss: 8.6; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits: 0; none known

Shaarli is a personal bookmarking service. Versions prior to 0.16.3 are vulnerable to stored XSS in `application/front/controller/visitor/BookmarkListController.php`. The `permalink` handler concatenates the raw `$bookmark->getTitle()` into the `pagetitle` template variable and the RainTPL template emits it into the document `<title>` element without HTML escaping. A bookmark title containing `</title><script>...</script>` closes the document title early and the injected script executes in the Shaarli origin for any visitor of `/shaare/{hash}`. Shaarli's metadata fetcher copies a remote page's `<title>` text verbatim into the local bookmark title, so an attacker who hosts an attacker-controlled URL and convinces an administrator to bookmark it plants the payload with no further interaction — and the resulting permalink fires for every visitor including the administrator on first save, providing a one-shot administrator account takeover. Version 0.16.3 fixes the issue.

Patch / fix

fixed in 1

shaarli_project shaarli 0.16.3

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: total
Assessed: 2 mo ago (2026-08-20)

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/shaarli/Shaarli/security/advisories/GHSA-xm98-h5jj-64xv referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.6	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
CNA	4.0	8.6	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

shaarli Shaarli

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

github.com /shaarli/Shaarli/security/advisories/GHSA-xm98-h5jj-64xv
exploit

Sources

CVE List CVE-2026-50190
NVD CVE-2026-50190

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary