CVE-2021-3989Network attack vector

Untrusted redirects via unchecked login destination

Published Dec 1, 2021 · Updated Aug 3, 2024

Open redirect in ShowDoc before 2.9.13 allows remote attackers to send authenticated users to untrusted sites through crafted login URLs. The Login.vue component decodes the redirect query parameter and uses it after login or session detection without restricting absolute destinations. Exploitation requires a user to follow the crafted URL and complete or already hold a valid session; the redirect supports phishing but does not alter ShowDoc data.

CVSS severity6.5
Medium
EPSS probability0.76%
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 ShowDoc before 2.9.13 allows remote attackers to send authenticated users to untrusted sites through crafted login URLs. The Login.vue component decodes the redirect query parameter and uses it after login or session detection without restricting absolute destinations. Exploitation requires a user to follow the crafted URL and complete or already hold a valid session; the redirect supports phishing but does not alter ShowDoc data.

The record

CVE
CVE-2021-3989
Published
Dec 1, 2021
Updated
Aug 3, 2024
Vendor
ShowDoc
Product
ShowDoc
Classifications
CWE-601
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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 <2.9.13

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ShowDoc · ShowDocversion=unspecified <2.9.13

Published CVSS scores

6.1GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.5@huntrdevCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/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 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 exploitUnconfirmed

Weakness, pattern, technique

CWE-601URL Redirection to Untrusted Site

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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