CVE-2024-45047Public exploitNetwork attack vector

Cross-site scripting via unescaped attribute less-than signs

Published Aug 30, 2024 · Updated Aug 30, 2024

Mutation XSS in Svelte before 4.2.19 allows remote attackers to execute JavaScript through untrusted server-rendered attributes. The server-side renderer escapes quotation marks and ampersands in attribute values but leaves less-than signs unescaped, allowing a crafted value inside a noscript element to mutate into executable markup when a browser parses it. Exploitation requires an application to place attacker-controlled data in such an attribute and a user to load the rendered page, exposing browser-accessible data and actions.

CVSS severity5.4
Medium
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Mutation XSS in Svelte before 4.2.19 allows remote attackers to execute JavaScript through untrusted server-rendered attributes. The server-side renderer escapes quotation marks and ampersands in attribute values but leaves less-than signs unescaped, allowing a crafted value inside a noscript element to mutate into executable markup when a browser parses it. Exploitation requires an application to place attacker-controlled data in such an attribute and a user to load the rendered page, exposing browser-accessible data and actions.

The record

CVE
CVE-2024-45047
Published
Aug 30, 2024
Updated
Aug 30, 2024
Vendor
Svelte
Product
Svelte
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 30, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 30, 2024Record 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=0 <4.2.19
  2. Affected versionversion=< 4.2.19

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Svelte · Svelteversion=0 <4.2.19; version=< 4.2.19

Published CVSS scores

5.4GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A: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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

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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