CVE-2026-57580

CRITICALPre-NVD 9.49.4—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 63% 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, secondary
9.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.4Exploit: None knownExposed: 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. 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.

CVSS v3
9.4
EG Score
9.4(medium)
EG Risk
57(Track)
EG Risk 57/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity94% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
37%
KEV
Not listed

Published

August 18, 2026

Last Modified

August 18, 2026

Advisory Details (5)

Auto-updated Aug 22, 2026
Patch available. Sources: github_pr, github, github_commit.
github Patch Available

Account Takeover via SAML NameID Comment Truncation · Advisory · goauthentik/authentik · GitHub

https://github.com/goauthentik/authentik/security/advisories/GHSA-35v6-hv2g-6992
github_pr

security: automated internal backport of patch 1934.sec.patch to authentik-2026.5

Fix merged in goauthentik/authentik PR #24062 on 2026-07-15 — awaiting tagged release

https://github.com/goauthentik/authentik/pull/24062
github_pr

security: automated internal backport of patch 1934.sec.patch to authentik-2026.2

Fix merged in goauthentik/authentik PR #24057 on 2026-07-15 — awaiting tagged release

https://github.com/goauthentik/authentik/pull/24057
github_commit

commit 8704a1b89d7b (goauthentik/authentik)

Fix landed in goauthentik/authentik commit 8704a1b89d7b — awaiting tagged release

https://github.com/goauthentik/authentik/commit/8704a1b89d7bf46bcef0d3c434c821b937fdecc3
github_commit

commit 6bd00f09f1f6 (goauthentik/authentik)

Fix landed in goauthentik/authentik commit 6bd00f09f1f6 — awaiting tagged release

https://github.com/goauthentik/authentik/commit/6bd00f09f1f6b5bc5212a10340418fa1b264f02c

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 16× 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.

  1. 2026-08-25 16:36 UTCEG score recompute
  2. 2026-08-25 13:49 UTCEPSS rescore
  3. 2026-08-24 17:33 UTCEG score recompute
  4. 2026-08-24 09:54 UTCEG score recompute
  5. 2026-08-23 03:12 UTCEG score recompute
  6. 2026-08-23 00:19 UTCEPSS rescore
  7. 2026-08-22 00:21 UTCEG score recompute
  8. 2026-08-21 23:49 UTCEPSS rescore
  9. 2026-08-21 01:27 UTCEG score recompute
  10. 2026-08-20 22:55 UTCEPSS rescore
  11. 2026-08-19 18:15 UTCEG score recompute
  12. 2026-08-19 17:04 UTCEPSS rescore
  13. 2026-08-18 18:23 UTCEG score recompute
  14. 2026-08-18 17:57 UTCEG score recompute
  15. 2026-08-18 17:17 UTCEG score recompute
  16. 2026-08-18 17:14 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-57580?
CVE-2026-57580 is a critical vulnerability published on August 18, 2026. 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 USERNAMELINK or EMAILLINK user-matching mode interprets an XML comment in a NameID differently from the identity provider's signed assertion. An attacker with an…
When was CVE-2026-57580 disclosed?
CVE-2026-57580 was first published in the National Vulnerability Database on August 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-57580 actively exploited?
CVE-2026-57580 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 63.4% of all scored CVEs.
What is the CVSS score of CVE-2026-57580?
CVE-2026-57580 has a CVSS v3 base score of 9.4 (NVD).
How do I remediate CVE-2026-57580?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-57580, 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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