CVE-2021-22171Public exploitNetwork attack vector

API token theft via OAuth code redirection

Published Jan 15, 2021 · Updated Aug 3, 2024

Improper authentication in GitLab Pages allows remote attackers to steal a victim's API token when the victim opens a crafted link. The domainAllowed check accepts a domain registered to a Pages project without verifying DNS control, allowing an OAuth authorization code to be redirected to an attacker-controlled domain. Exploitation requires victim interaction and enables unauthorized access to private Pages content, with no established data modification or service interruption.

CVSS severity6.5
Medium
EPSS probability1.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in GitLab Pages allows remote attackers to steal a victim's API token when the victim opens a crafted link. The domainAllowed check accepts a domain registered to a Pages project without verifying DNS control, allowing an OAuth authorization code to be redirected to an attacker-controlled domain. Exploitation requires victim interaction and enables unauthorized access to private Pages content, with no established data modification or service interruption.

The record

CVE
CVE-2021-22171
Published
Jan 15, 2021
Updated
Aug 3, 2024
Vendor
GitLab
Product
GitLab
Classifications
CWE-287, T1528
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 15, 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=>=11.5.0, <13.5.6
  2. Affected versionversion=>=13.6.0, <13.6.4
  3. Affected versionversion=>=13.7.0, <13.7.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

GitLab · GitLabversion=>=11.5.0, <13.5.6; version=>=13.6.0, <13.6.4; version=>=13.7.0, <13.7.2

Published CVSS scores

6.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/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 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-287Improper Authentication
T1528Steal Application Access Token

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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