CVE-2026-40165

HIGHNVD 8.78.7—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.7 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 69% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
8.7
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 8.7Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

authentik is an open-source identity provider. Versions 2025.12.4 and prior, and versions 2026.2.0-rc1 through 2026.2.2 were vulnerable to Authentication Bypass through SAML NameID XML Comment Injection. Due to how authentik extracted the NameID value from a SAML assertion, it was possible for an attacker to trick authentik into only seeing a part of the NameID value, potentially allowing an attacker to gain access to other accounts. This issue could be exploited on an authentik instance with a SAML Source, where the attacker had an account on the SAML Source and the ability to modify their NameID value (commonly username or E-mail), and XML Signing was enabled. The attacker could modify the SAML assertion given to authentik by injecting a comment within the NameID value, which effectively truncated the NameID value to the snippet before the comment, and gave the attacker access to any user account. This issue has been fixed in versions 2025.12.5 and 2026.2.3.

CVSS v3
8.7
EG Score
8.7(medium)
EPSS
31.4%
KEV
Not listed

Published

May 21, 2026

Last Modified

May 21, 2026

Advisory Details (2)

Auto-updated Jun 3, 2026
Patch available. Sources: github_commit, github.
github Patch Available

SAML NameID XML Comment Injection Enables Authentication Bypass via Identifier Truncation · Advisory · goauthentik/authentik · GitHub

https://github.com/goauthentik/authentik/security/advisories/GHSA-9wj8-xv4r-qwrp
github_commit

commit 47dec5c6b7fb (goauthentik/authentik)

Fix landed in goauthentik/authentik commit 47dec5c6b7fb — awaiting tagged release

https://github.com/goauthentik/authentik/commit/47dec5c6b7fb4a62bfad2ae8bddf002bde7ba774

Weakness Classification(3)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 53× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 116 total refreshes for this CVE.

  1. 2026-07-11 08:27 UTCEPSS rescore
  2. 2026-07-09 19:10 UTCEPSS rescore
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  1. 2026-06-24 14:05 UTCEPSS rescore
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  27. 2026-06-12 14:44 UTCEG score recompute
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  40. 2026-06-08 14:17 UTCEPSS rescore
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  44. 2026-06-07 15:25 UTCEPSS rescore
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  46. 2026-06-07 12:21 UTCEG score recompute
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  61. 2026-06-04 07:33 UTCEG score recompute
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  65. 2026-06-02 20:13 UTCEPSS rescore
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  73. 2026-05-31 22:30 UTCEPSS rescore
  74. 2026-05-31 22:30 UTCEPSS rescore
  75. 2026-05-31 00:16 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2026-40165?
CVE-2026-40165 is a high vulnerability published on May 21, 2026. authentik is an open-source identity provider. Versions 2025.12.4 and prior, and versions 2026.2.0-rc1 through 2026.2.2 were vulnerable to Authentication Bypass through SAML NameID XML Comment Injection. Due to how authentik extracted the NameID value from a SAML assertion, it was possible for an…
When was CVE-2026-40165 disclosed?
CVE-2026-40165 was first published in the National Vulnerability Database on May 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40165 actively exploited?
CVE-2026-40165 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 31.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-40165?
CVE-2026-40165 has a CVSS v3 base score of 8.7 (NVD).
How do I remediate CVE-2026-40165?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40165, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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