CVE-2023-20883Network attack vector

Service interruption via cacheable welcome-page 404 responses

Published May 26, 2023 · Updated Jan 16, 2025

Denial of service in Spring Boot allows remote attackers to interrupt access to a welcome page through a caching reverse proxy. WelcomePageHandlerMapping declines requests whose Accept header excludes text/html, letting fallback resource handling return a cacheable 404 for the root path instead of 406. Exploitation requires Spring MVC auto-configuration, static or templated welcome-page support, and a proxy that caches 404 responses, allowing a crafted request to deny the cached root page to later clients.

CVSS severity7.5
High
EPSS probability0.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Spring Boot allows remote attackers to interrupt access to a welcome page through a caching reverse proxy. WelcomePageHandlerMapping declines requests whose Accept header excludes text/html, letting fallback resource handling return a cacheable 404 for the root path instead of 406. Exploitation requires Spring MVC auto-configuration, static or templated welcome-page support, and a proxy that caches 404 responses, allowing a crafted request to deny the cached root page to later clients.

The record

CVE
CVE-2023-20883
Published
May 26, 2023
Updated
Jan 16, 2025
Vendor
Spring
Product
Spring Boot
Classifications
CWE-400, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 26, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 16, 2025Record 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=Spring Boot versions 3.0.0 - 3.0.6, 2.7.0 - 2.7.11, 2.6.0 - 2.6.14, 2.5.0 - 2.5.14 and older unsupported versions

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Spring · Spring Bootversion=Spring Boot versions 3.0.0 - 3.0.6, 2.7.0 - 2.7.11, 2.6.0 - 2.6.14, 2.5.0 - 2.5.14 and older unsupported versions

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

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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