CVE-2020-11053Public exploitNetwork attack vector

Open redirect via encoded-whitespace validation bypass

Published May 7, 2020 · Updated Aug 4, 2024

Open redirect in OAuth2 Proxy before 5.1.1 allows remote attackers to send authenticated users to arbitrary sites via crafted URLs. The IsValidRedirect method treats a leading slash as a local path without rejecting HTML-encoded whitespace before a second slash or backslash. A victim must follow the crafted link and complete the authentication flow before the proxy issues the attacker-controlled redirect.

CVSS severity7.1
High
EPSS probability0.79%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Open redirect in OAuth2 Proxy before 5.1.1 allows remote attackers to send authenticated users to arbitrary sites via crafted URLs. The IsValidRedirect method treats a leading slash as a local path without rejecting HTML-encoded whitespace before a second slash or backslash. A victim must follow the crafted link and complete the authentication flow before the proxy issues the attacker-controlled redirect.

The record

CVE
CVE-2020-11053
Published
May 7, 2020
Updated
Aug 4, 2024
Vendor
OAuth2 Proxy
Product
OAuth2 Proxy
Classifications
CWE-601, CAPEC-178, T1566.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 7, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=< 5.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OAuth2 Proxy · OAuth2 Proxyversion=< 5.1.1

Published CVSS scores

5.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:N
7.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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.

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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-601URL Redirection to Untrusted Site ('Open Redirect')
CAPEC-178Cross-Site Flashing
T1566.002Spearphishing Link

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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