CVE-2021-29456
CVE-2021-29456 is a medium-severity vulnerability in Authelia with a CVSS 3.x base score of 5.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-601.
Key facts
- Severity: Medium (CVSS 3.x base score 5.7)
- CVSS v2: 4.9
- EPSS exploit prediction: 1% (40th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-601
- Affected product: Authelia
- Published:
- Last modified:
Description
Authelia is an open-source authentication and authorization server providing 2-factor authentication and single sign-on (SSO) for your applications via a web portal. In versions 4.27.4 and earlier, utilizing a HTTP query parameter an attacker is able to redirect users from the web application to any domain, including potentially malicious sites. This security issue does not directly impact the security of the web application itself. As a workaround, one can use a reverse proxy to strip the query parameter from the affected endpoint. There is a patch for version 4.28.0.
Frequently asked questions
- What is CVE-2021-29456?
- Authelia is an open-source authentication and authorization server providing 2-factor authentication and single sign-on (SSO) for your applications via a web portal. In versions 4.27.4 and earlier, utilizing a HTTP query parameter an attacker is able to redirect users from the web application to any domain, including potentially malicious sites. This security issue does not directly impact the security of the web application itself. As a workaround, one can use a reverse proxy to strip the query parameter from the affected endpoint. There is a patch for version 4.28.0.
- How severe is CVE-2021-29456?
- CVE-2021-29456 has a CVSS 3.x base score of 5.7, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is none, integrity high, and availability none.
- Is CVE-2021-29456 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-29456?
- CVE-2021-29456 affects Authelia. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2021-29456?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- When was CVE-2021-29456 published?
- CVE-2021-29456 was published on 2021-04-21 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:authelia:authelia:*:*:*:*:*:*:*:*
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