VDB-347269 · CVE-2026-27121 · GHSA-f7gr-6p89-r883

sveltejs svelte up to 5.51.4 Element Attribute cross site scripting

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
2.3	$0-$5k	0.00

Summaryinfo

A vulnerability classified as problematic has been found in sveltejs svelte up to 5.51.4. Affected is an unknown function of the component Element Attribute Handler. This manipulation causes cross site scripting. The identification of this vulnerability is CVE-2026-27121. It is possible to initiate the attack remotely. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability has been found in sveltejs svelte up to 5.51.4 and classified as problematic. Affected by this vulnerability is some unknown processing of the component Element Attribute Handler. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. The summary by CVE is:

svelte performance oriented web framework. Versions of svelte prior to 5.51.5 are vulnerable to cross-site scripting (XSS) during server-side rendering. When using spread syntax to render attributes from untrusted data, event handler properties are included in the rendered HTML output. If an application spreads user-controlled or external data as element attributes, an attacker can inject malicious event handlers that execute in victims' browsers. This vulnerability is fixed in 5.51.5.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-27121 since 02/17/2026. The exploitation appears to be easy. The attack can be launched remotely. Additional levels of successful authentication are needed for exploitation. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1059.007 for this issue.

Upgrading to version 5.51.5 eliminates this vulnerability.

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Productinfo

Vendor

sveltejs

Name

svelte

Version

Website

Product: https://github.com/sveltejs/svelte/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 2.4
VulDB Meta Temp Score: 2.3

VulDB Base Score: 2.4
VulDB Temp Score: 2.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: svelte 5.51.5

Timelineinfo

02/17/2026 CVE reserved
02/21/2026 +4 days Advisory disclosed
02/21/2026 +0 days VulDB entry created
02/22/2026 +1 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-f7gr-6p89-r883
Status: Confirmed

CVE: CVE-2026-27121 (🔒)
GCVE (CVE): GCVE-0-2026-27121
GCVE (VulDB): GCVE-100-347269

Entryinfo

Created: 02/21/2026 05:56
Updated: 02/22/2026 20:54
Changes: 02/21/2026 05:56 (68), 02/22/2026 20:54 (1)
Complete: 🔍
Cache ID: 216::103