CVE-2020-21038Public exploitNetwork attack vector

Post-login phishing redirect via unchecked referer

Published May 8, 2023 · Updated Jan 29, 2025

Open redirect in Typecho 1.1-17.10.30-release allows remote attackers to redirect users after authentication via a crafted Login.php referer parameter. Login.php passes the user-controlled referer to Response::redirect, while safeUrl permits absolute HTTP and HTTPS URLs without requiring the destination host to match the Typecho site. A victim must follow the crafted login URL and authenticate, after which the redirect sends the victim to an attacker-controlled phishing site.

CVSS severity6.1
Medium
EPSS probability0.46%
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 Typecho 1.1-17.10.30-release allows remote attackers to redirect users after authentication via a crafted Login.php referer parameter. Login.php passes the user-controlled referer to Response::redirect, while safeUrl permits absolute HTTP and HTTPS URLs without requiring the destination host to match the Typecho site. A victim must follow the crafted login URL and authenticate, after which the redirect sends the victim to an attacker-controlled phishing site.

The record

CVE
CVE-2020-21038
Published
May 8, 2023
Updated
Jan 29, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-601, T1566.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 8, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 29, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.1CISA-ADPCVSS: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 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-601URL Redirection to Untrusted Site ('Open Redirect')
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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