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Vulnerability details: VCID-v4yv-krg8-tkhd
Vulnerability ID VCID-v4yv-krg8-tkhd
Aliases CVE-2026-27121
GHSA-f7gr-6p89-r883
Summary Svelte affected by cross-site scripting via spread attributes in Svelte SSR 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.
Status Published
Exploitability 0.5
Weighted Severity 6.2
Risk 3.1
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3 5.6 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-27121.json
epss 0.00011 https://api.first.org/data/v1/epss?cve=CVE-2026-27121
cvssv3.1_qr MODERATE https://github.com/advisories/GHSA-f7gr-6p89-r883
cvssv4 5.1 https://github.com/sveltejs/svelte
generic_textual MODERATE https://github.com/sveltejs/svelte
cvssv3.1_qr MODERATE https://github.com/sveltejs/svelte/security/advisories/GHSA-f7gr-6p89-r883
cvssv4 5.1 https://github.com/sveltejs/svelte/security/advisories/GHSA-f7gr-6p89-r883
generic_textual MODERATE https://github.com/sveltejs/svelte/security/advisories/GHSA-f7gr-6p89-r883
ssvc Track https://github.com/sveltejs/svelte/security/advisories/GHSA-f7gr-6p89-r883
cvssv4 5.1 https://nvd.nist.gov/vuln/detail/CVE-2026-27121
generic_textual MODERATE https://nvd.nist.gov/vuln/detail/CVE-2026-27121
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-27121.json
https://api.first.org/data/v1/epss?cve=CVE-2026-27121
https://github.com/sveltejs/svelte
2441532 https://bugzilla.redhat.com/show_bug.cgi?id=2441532
CVE-2026-27121 https://nvd.nist.gov/vuln/detail/CVE-2026-27121
GHSA-f7gr-6p89-r883 https://github.com/advisories/GHSA-f7gr-6p89-r883
GHSA-f7gr-6p89-r883 https://github.com/sveltejs/svelte/security/advisories/GHSA-f7gr-6p89-r883
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-27121.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N Found at https://github.com/sveltejs/svelte
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N Found at https://github.com/sveltejs/svelte/security/advisories/GHSA-f7gr-6p89-r883
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-02-23T19:31:36Z/ Found at https://github.com/sveltejs/svelte/security/advisories/GHSA-f7gr-6p89-r883
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N Found at https://nvd.nist.gov/vuln/detail/CVE-2026-27121
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.01429
EPSS Score 0.00011
Published At May 30, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-05-30T21:06:43.908640+00:00 GitLab Importer Import https://gitlab.com/gitlab-org/advisories-community/-/blob/main/npm/svelte/CVE-2026-27121.yml 38.6.0