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CVE-2026-57580— authentik: Account Takeover via SAML NameID Comment Truncation

Quick assessment

Affected
goauthentik authentik
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Authentik Security authentik是Authentik Security组织的一个用于现代 SSO 的开源身份提供商 (IdP)。 Authentik Security authentik 2026.2.6之前版本和2026.5.0至2026.5.5之前版本存在处理逻辑错误漏洞，该漏洞源于对NameID中XML注释的解释不一致，可能导致攻击者通过特制NameID将外部身份绑定到受害者现有账户，实现完全接管。

CVSS 9.4 · Critical EPSS 0.44% · P37

Possible ATT&CK Techniques 1 AI

T1199 · Trusted Relationship

Affected Version Matrix 2

VendorProduct Version RangeStatus
goauthentik authentik < 2026.2.6 affected
>= 2026.5.0, < 2026.5.5 affected
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I. Basic Information for CVE-2026-57580

Vulnerability Information
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Vulnerability Title
authentik: Account Takeover via SAML NameID Comment Truncation
Source: CVE Program / CVE List V5
Vulnerability Description
authentik is an open-source identity provider. Prior to 2026.2.6 and 2026.5.5, an inbound SAML Source configured with the non-default USERNAME_LINK or EMAIL_LINK user-matching mode interprets an XML comment in a NameID differently from the identity provider's signed assertion. An attacker with an account on the source identity provider who can set the account's NameID can inject an XML comment that truncates the value used by authentik to the text before the comment while the signed assertion remains valid. A crafted NameID can therefore truncate to a victim's username or email and bind the attacker's external identity to the victim's existing account. This grants full takeover without the victim's password or the identity provider's private key, and the malicious link persists so later logins succeed without the comment. Sources using the default unique-identifier matching mode and authentik's outbound SAML Provider role are not affected. This issue is fixed in versions 2026.2.6 and 2026.5.5.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
解释冲突
Source: CVE Program / CVE List V5
Vulnerability Title
Authentik Security authentik 处理逻辑错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Authentik Security authentik是Authentik Security组织的一个用于现代 SSO 的开源身份提供商 (IdP)。 Authentik Security authentik 2026.2.6之前版本和2026.5.0至2026.5.5之前版本存在处理逻辑错误漏洞，该漏洞源于对NameID中XML注释的解释不一致，可能导致攻击者通过特制NameID将外部身份绑定到受害者现有账户，实现完全接管。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
goauthentik authentik < 2026.2.6 -

II. Public POCs for CVE-2026-57580

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Qwen3.6-35B-A3B · 7821 chars
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III. Intelligence Information for CVE-2026-57580

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Patches & Fixes for CVE-2026-57580 (4)

Vendor Advisories for CVE-2026-57580 (1)

Vendor Pages for CVE-2026-57580 (2)

Same Patch Batch · goauthentik · 2026-08-18 · 4 CVEs total

CVE-2026-61574 8.8 HIGH authentik RAC: access any endpoint via an unrelated application
CVE-2026-54730 8.6 HIGH authentik: Authentication Flow Bypass via Unguarded challenge_valid() in AuthenticatorEndp
CVE-2026-55106 5.3 MEDIUM authentik: Unauthenticated LDAP directory data disclosure

IV. Related Vulnerabilities

Same product: authentik
Same vendor: goauthentik
Same weakness: CWE-436

V. Comments for CVE-2026-57580

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