CVE-2020-5401Public exploitNetwork attack vector

Service interruption via cacheable instance-routing errors

Published Feb 27, 2020 · Updated Sep 16, 2024

Cache poisoning in GoRouter in Cloud Foundry Routing Release before 0.197.0 allows remote attackers to interrupt application access via HTTP headers. The lookup handler returns a cacheable 404 response when X-CF-APP-INSTANCE names a nonexistent instance instead of treating the request as invalid. No authentication is required, but an intervening cache must store that response before legitimate requests are blocked.

CVSS severity5.3
Medium
EPSS probability1.04%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cache poisoning in GoRouter in Cloud Foundry Routing Release before 0.197.0 allows remote attackers to interrupt application access via HTTP headers. The lookup handler returns a cacheable 404 response when X-CF-APP-INSTANCE names a nonexistent instance instead of treating the request as invalid. No authentication is required, but an intervening cache must store that response before legitimate requests are blocked.

The record

CVE
CVE-2020-5401
Published
Feb 27, 2020
Updated
Sep 16, 2024
Vendor
Cloud Foundry Foundation
Product
Routing Release
Classifications
CWE-393, CWE-444, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 27, 2020CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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=unspecified <0.197.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Cloud Foundry Foundation · Routing Releaseversion=unspecified <0.197.0

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 exploitPublished

Weakness, pattern, technique

CWE-393Return of Wrong Status Code
CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1499Endpoint Denial of Service

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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