CVE-2026-47201: authentik: XML Signature Wrapping in SAML Source ACS allows authentication as arbitrary federated user
Vulnerability summary
CVE-2026-47201 is a high (CVSS 8.5) Improper Input Validation vulnerability in goauthentik authentik. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7.8% of scored vulnerabilities.
Not severe (CVSS 8.5, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Timeline
- 02-06-2026PublishedVulnerability first disclosed.
- 03-06-2026Last modifiedVulnerability information updated.
Description
authentik is an open-source identity provider. Prior to versions 2025.12.5, 2026.2.3, and 2026.5.1, authentik's SAML Source ACS endpoint is vulnerable to XML Signature Wrapping when validating upstream SAML responses. An attacker with any account at the upstream IdP can reuse a valid signed assertion to authenticate as another federated user. This issue has been patched in versions 2025.12.5, 2026.2.3, and 2026.5.1.
CVSS metrics
3 scores · 3 sources · 1 version- OSV · GoEcosystem advisory · calculated8.5HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
- NVDNIST8.5HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
EPSS trend
Probability
0.18%
Chance of exploitation in the next 30 days
Percentile
8%
Versus all other CVEs
30-day change
Decrease -0.10 pp
From 0.28% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
- CWE-347Improper Verification of Cryptographic SignatureThe product does not verify, or incorrectly verifies, the cryptographic signature for data.
Affected systems
Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Go1 product
- goauthentik.io< 0.0.0-20260528144335-a370d76d23c7
Goauthentik1 product
- authentik< 2025.12.5 | < 2026.2.3 | < 2026.5.1 | < 2025.12.6 | ≥ 2026.2.0, < 2026.2.4 | ≥ 2026.5.0, < 2026.5.1
2 vendors · 2 products
References
4 links- github.com/goauthentik/authentik/security/advisories/GHSA-c3m2-jqmq-pvp3X Refsource CONFIRMWEBMitigationVendor Advisory
