CVE-2026-49757

CRITICALPre-NVD 9.29.2—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6%, top 52% 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
Elevated
9.2EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.7%CVSS: 9.2Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

Authentication Bypass by Spoofing vulnerability in team-alembic AshAuthentication allows account takeover of local users via OAuth2/OIDC sign-in.

AshAuthentication's OAuth2 and OIDC family strategies matched the local user by email address (an upsert on the email field, or a user-defined sign-in filter) rather than by the OpenID Connect iss/sub claim combination. Per OpenID Connect Core §5.7, only iss/sub uniquely and stably identifies an end-user; other claims, including email, MUST NOT be used as unique identifiers.

A provider login presenting a victim's email, including an unverified email, a reused email, or an account with email_verified: false, resolved to and signed in as the victim's existing local account. An unauthenticated attacker who can register an account on any accepted OAuth provider with the victim's email (or who benefits from provider-side email reuse or reclamation) obtains the victim's full local privileges.

The fix resolves users by the (strategy, sub) identity stored in a user identity resource, and only links a new sub to an existing local account by email when the provider's email_verified claim is trusted (trust_email_verified?).

This issue affects ash_authentication from 0.1.0 before 4.14.0 and from 5.0.0-rc.0 before 5.0.0-rc.10.

CVSS v3
9.2
EG Score
9.2CRITICALmedium confidence
EG Risk
72
EG Risk 72/100

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
Severity92% × 45%
Exploitation40% × 40%
Automatability100% × 15%
EPSS PROB
0.7%
EPSS %ILE
51st
KEV
Not listed

Published

June 15, 2026

Last Modified

June 15, 2026

Advisory Details (5)

Auto-updated Sep 15, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github.
generic

OSV - Open Source Vulnerabilities

https://osv.dev/vulnerability/EEF-CVE-2026-49757
githubMentions a patch (unverified)🟡 PoC Available

OAuth2/OIDC account takeover via email-based user matching · Advisory · team-alembic/ash_authentication · GitHub

https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-777c-2fxx-qr28
github_commit Patch Available

commit 728b8d28c1b5 (team-alembic/ash_authentication)

Patch available: team-alembic/ash_authentication v4.14.0 (contains commit 728b8d28c1b5)

https://github.com/team-alembic/ash_authentication/commit/728b8d28c1b5f465fa1116ef044a815300fc733d
github_commit Patch Available

commit 64530644f9b3 (team-alembic/ash_authentication)

Patch available: team-alembic/ash_authentication v5.0.0-rc.10 (contains commit 64530644f9b3)

https://github.com/team-alembic/ash_authentication/commit/64530644f9b37ebb76ca14aeb83a77597a0034b7
generic

CVE-2026-49757

https://cna.erlef.org/cves/CVE-2026-49757.html

Vendor Advisories for CVE-2026-49757(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
Hex(1)
PackageVulnerable rangeFix by version rangeDependents
ash_authentication5.0.0-rc.0 ... 5.0.0-rc.9 (10 versions)
  • 0.1.0 up to 4.14.0: fixed in 4.14.0
  • 5.0.0-rc.0 up to 5.0.0-rc.10: fixed in 5.0.0-rc.10
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 23× 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 143 total refreshes for this CVE.

  1. 2026-10-10 20:00 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2026-49757?
CVE-2026-49757 is a critical vulnerability published on June 15, 2026. Authentication Bypass by Spoofing vulnerability in team-alembic AshAuthentication allows account takeover of local users via OAuth2/OIDC sign-in. AshAuthentication's OAuth2 and OIDC family strategies matched the local user by email address (an upsert on the email field, or a user-defined sign-in…
When was CVE-2026-49757 disclosed?
CVE-2026-49757 was first published on June 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-49757 actively exploited?
CVE-2026-49757 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (51st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-49757?
CVE-2026-49757 has a CVSS base score of 9.2 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-49757?
A fix for CVE-2026-49757 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-49757 are linked in the Vendor Advisories panel on this page.

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