CVE-2026-49757: Authentication Bypass by Spoofing vulnerability in team-alembic AshAuthentication allows account takeover of l

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CRITICAL 9.2REMOTE

CVE-2026-49757 is a critical-severity flaw (CVSS 9.2) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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-us

Why this priority

Critical severity
CISA SSVC: public proof of concept
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.2 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 51%)
CISA exploited list	No
Weakness	CWE-290
Published	2026-06-15
Last modified	2026-10-25

Publisher (CNA): EEF

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-06-15 12:16 UTCPublished CVE record published
2026-10-25 23:10 UTCUpdated Record last modified

Exact fixes by distribution

Fedora 46 · log4cplus · FIXED · 2.2.0.1-2.fc46 · FEDORA-2026-fc241370c9 · source

sudo dnf upgrade --advisory=FEDORA-2026-fc241370c9

Fedora ELN · velocitty · FIXED · 1.0.3-2.eln159 · FEDORA-2026-edae8cd295 · source

sudo dnf upgrade --advisory=FEDORA-2026-edae8cd295

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: Hunt-Benito/ash-authentication-oauth2-oidc-account-takeover-cve-2026-49757-email-based-user-matching (0 stars)
Write-up: cna.erlef.org/cves/CVE-2026-49757.html
Write-up: github.com/team-alembic/ash_authentication/security/advisories/GHSA-777c-2fxx-qr28

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-49757?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-49757 being exploited?

CVE-2026-49757 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-49757 affect?

CVE-2026-49757 affects affected software. Severity is critical (CVSS 9.2). 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

How urgent is CVE-2026-49757?

Priority 55/100. Critical severity; CISA SSVC: public proof of concept; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

References

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