CVE-2026-27901Network attack vector

Cross-site scripting via unescaped contenteditable bindings

Published Feb 26, 2026 · Updated Feb 26, 2026

Cross-site scripting in Svelte before 5.53.5 allows remote attackers to execute script in users' browsers through server-rendered bindings. The server compiler's build_element_attributes path emits initial contenteditable bind:innerText and bind:textContent values without calling the escape helper, so attacker-controlled markup enters the HTML response. Exploitation requires an application to server-render untrusted initial binding data and a user to load the affected page; impact is confined to the user's browser context.

CVSS severity5.3
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Svelte before 5.53.5 allows remote attackers to execute script in users' browsers through server-rendered bindings. The server compiler's build_element_attributes path emits initial contenteditable bind:innerText and bind:textContent values without calling the escape helper, so attacker-controlled markup enters the HTML response. Exploitation requires an application to server-render untrusted initial binding data and a user to load the affected page; impact is confined to the user's browser context.

The record

CVE
CVE-2026-27901
Published
Feb 26, 2026
Updated
Feb 26, 2026
Vendor
Svelte
Product
Svelte
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 5.53.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Svelte · Svelteversion=< 5.53.5

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
5.3GitHub, Inc.CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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