NVD / CVE Program· CNA VulnCheck

CVE-2026-80192: better-auth SSO before 1.6.27 Domain Ownership Authentication Bypass

HighCVSS 8.6 · v4.0—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 34/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.36% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
Fixed version: better-auth sso 1.4.8, 1.6.27, 1.7.0-rc.5.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to better-auth sso 1.4.8, 1.6.27, 1.7.0-rc.5 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

@better-auth/sso before 1.6.27 (and before 1.4.8 in the 1.4.x line and before 1.7.0-rc.5 in the 1.7 prerelease line) contains two domain-ownership flaws. When domain verification is disabled, automatic organization assignment accepts unverified provider domains, allowing an authenticated organization owner/administrator to register an SSO provider for an arbitrary domain and have users with matching email domains added to the attacker's organization with default member permissions. When domain verification is enabled, a race condition between the verify-domain and update-provider endpoints can apply completed DNS proof to a different domain; combined with implicit account linking, this can link an attacker-controlled identity provider to an existing user account. Exploitation requires the SSO plugin (and, for the org-assignment path, the organization plugin) with the relevant configuration enabled.

EUVD-2026-66214

Published: Aug 26, 2026
Updated: Oct 8, 2026
EPSS: 0.3% · 30th percentile
CWE: CWE-287

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 34 / 40 · 8.6 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.3%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · VulnCheck: 8.6; NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

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Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

better-auth sso
- 1.4.8, 1.6.27, 1.7.0-rc.5not affected
- 1.4.8-beta.1 and later · before 1.4.8affected · semver
- 1.4.9 and later · before 1.6.27affected · semver
- 1.7.0-beta.0 and later · before 1.7.0-rc.5affected · semver

Same product

better-auth: all records

Other highest-scoring records for the same primary product.

CVE-2026-110863Better Auth @better-auth/sso before 1.7.3 Authentication Bypass via Personal SSO Providers
34Monitor
CVE-2026-67328@better-auth/sso before 1.6.21 Account Takeover via SSO
34Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
better-auth sso	1.4.8	Vendor (CNA)
better-auth sso	1.6.27	Vendor (CNA)
better-auth sso	1.7.0-rc.5	Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-11086349 days apartBetter Auth @better-auth/sso before 1.7.3 Authentication Bypass via Personal SSO Providers
34Monitor

Bug bounty scope

VercelHackerOne · paid

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-26-0912 · Aug 26, 2026(Better Auth Güvenlik Zafiyeti )

All national notices →

Not on record for this CVE: patch commit or PR link.

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
A low-privileged account is enough.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability

Attack vector: Network
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: X

Weakness class (CWE)

CWE-287 · Improper Authentication

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Root cause

Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.

The bug in code

The whole CWE-287 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1app.use("/admin", requireSession, adminRouter);
2

3// Route added later skips the middleware
4app.post("/admin-api/config", updateConfig);

Fixed

1const admin = express.Router();
2admin.use(requireSession, requireRole("admin"));
3

4admin.post("/config", updateConfig);
5app.use("/admin", admin);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Change log (1)

Fix✗ → ✓Sep 28, 2026, 10:10 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/better-auth/better-auth/security/advisories/GHSA-8c5h-wx78-2cfg

Show all references (1 more)

www.vulncheck.com/advisories/better-auth-sso-before-1.6.27-domain-ownership-authentication-bypass

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records