What is the CVSS score of CVE-2026-27902?

CVE-2026-27902 has a CVSS 3.1 base score of 5.4 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of Svelte are affected by CVE-2026-27902?

CVE-2026-27902 presents moderate security risk, a cross-site scripting vulnerability rated CVSS 5.4. Attackers could inject scripts to steal sessions or perform actions as authenticated users.. A patch is available.

How to fix or mitigate CVE-2026-27902?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

Svelte CVE-2026-27902

MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2026-02-26 security-advisories@github.com

GHSA-qgvg-pr8v-6rr3

XSS Svelte Red Hat

5.4

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

5.4 MEDIUM

AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Red Hat

4.2 MEDIUM

qualitative

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:55 vuln.today

Patch released

Mar 05, 2026 - 14:48 nvd

Patch available

CVE Published

Feb 26, 2026 - 02:16 nvd

MEDIUM 5.4

Blast Radius

ecosystem impact

† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth

1 npm packages depend on svelte (1 direct, 0 indirect)

Ecosystem-wide dependent count for version 5.53.0.

DescriptionGitHub Advisory

Svelte performance oriented web framework. Prior to version 5.53.5, errors from transformError were not correctly escaped prior to being embedded in the HTML output, causing potential HTML injection and XSS if attacker-controlled content is returned from transformError. Version 5.53.5 fixes the issue.

AnalysisAI

Improper output encoding in Svelte versions prior to 5.53.5 allows attackers to inject malicious HTML and execute arbitrary JavaScript in user browsers through unescaped error messages returned by the transformError function. An attacker who can control error content can exploit this XSS vulnerability to compromise application security and user data. …

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Vulnerability AssessmentAI

Risk Assessment	CVSS 5.4 (MEDIUM). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario	An attacker could exploit this vulnerability to compromise the affected system.
Remediation	A vendor patch is available — apply it immediately. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. …

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

Vendor StatusVendor

CVE-2026-27902 vulnerability details – vuln.today

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