Cyber Resilience

CVE-2026-31813

Auth Bypass in Supabase Auth ≤ 2.185.0

Auth Bypass
Published
11 March 2026
Modified
20 March 2026
Patch / advisory
View advisory
CVSS Score v3.1 4.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
EPSS Score 0.0014 3th percentile
Risk Priority 37 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-31813 is a medium-severity Authentication Bypass by Spoofing (CWE-290) vulnerability in Supabase Auth. Its CVSS base score is 4.8 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Adversary-in-the-Middle (T1557); ranked at the 3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to IA-2 (Identification and Authentication (Organizational Users)) and IA-3 (Device Identification and Authentication) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A07:2025 Authentication Failures

EU & UK References

Vulnerability Data

Supabase Auth is a JWT based API for managing users and issuing JWT tokens. Prior to 2.185.0, a vulnerability has been identified that allows an attacker to issue sessions for arbitrary users using specially crafted ID tokens when the Apple…

more

or Azure providers are enabled. The attacker issues a valid, asymmetrically signed ID token from their issuer for each victim email address, which then is sent to the Supabase Auth token endpoint using the ID token flow. If the ID token is OIDC compliant, the Auth server would validate it against the attacker-controlled issuer and link the existing OIDC identity (Apple or Azure) of the victim to an additional OIDC identity based on the ID token contents. The Auth server would then issue a valid user session (access and refresh tokens) at the AAL1 level to the attacker. This vulnerability is fixed in 2.185.0.

CWE(s)
CWE-290

Related Threats

MITRE ATT&CK Enterprise Techniques

T1557 Adversary-in-the-Middle Credential Access
Adversaries may attempt to position themselves between two or more networked devices using an adversary-in-the-middle (AiTM) technique to support follow-on behaviors such as [Network Sniffing](https://attack.
attack.mitre.org →
T1557.001 Name Resolution Poisoning and SMB Relay Credential Access
By responding to LLMNR/NBT-NS/mDNS network traffic, adversaries may spoof an authoritative source for name resolution to force communication with an adversary controlled system.
attack.mitre.org →
T1036 Masquerading Stealth
Adversaries may attempt to manipulate features of their artifacts to make them appear legitimate or benign to users and/or security tools.
attack.mitre.org →
T1036.001 Invalid Code Signature Stealth
Adversaries may attempt to mimic features of valid code signatures to increase the chance of deceiving a user, analyst, or tool.
attack.mitre.org →
T1134 Access Token Manipulation Stealth
Adversaries may modify access tokens to operate under a different user or system security context to perform actions and bypass access controls.
attack.mitre.org →
T1134.001 Token Impersonation/Theft Stealth
Adversaries may duplicate then impersonate another user's existing token to escalate privileges and bypass access controls.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-27389Shared CWE-290
CVE-2025-13953Shared CWE-290
CVE-2025-34063Shared CWE-290
CVE-2026-0834Shared CWE-290
CVE-2024-31784Shared CWE-290
CVE-2025-13635Shared CWE-290
CVE-2024-8901Shared CWE-290
CVE-2026-59916Shared CWE-290
CVE-2025-13455Shared CWE-290
CVE-2025-7448Shared CWE-290

Affected Assets

supabase
auth
≤ 2.185.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 3 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V6.4.3
  • V10.4.16
  • V10.5.1
  • V11.4.3

Mitigating Controls (NIST 800-53 r5) AI

IA-2 Identification and Authentication (Organizational Users) good match

Proper unique identification and authentication of users directly stops spoofing-based bypass of authentication.

IA-3 Device Identification and Authentication good match

Device identification and authentication before connection prevents spoofing of devices to bypass auth.

IA-8 Identification and Authentication (Non-organizational Users) good match

Authentication of non-organizational users blocks external spoofing attempts against the scheme.

IA-5 Authenticator Management good match

Authenticator management ensures credentials cannot be easily spoofed or reused to bypass authentication.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-04 full match
prevents

Protecting, conveying, and verifying identity assertions specifically prevents the spoofing that enables authentication bypass.

PR.AA-03 mostly match
prevents

Requiring authentication of users/services/hardware directly counters spoofing-based bypass when strong methods are used.

PR.AA-02 partial match
prevents

Proofing and binding identities reduces spoofing opportunities during enrollment but does not address runtime authentication implementation flaws.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.5 Secure authentication full match
degrades

Secure authentication control directly mitigates authentication bypass by spoofing.

A.5.17 Authentication information mostly match
degrades

Authentication information management directly addresses credential handling that prevents spoofing.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect spoofing vulnerabilities but does not prevent them by itself.

A.5.15 Access control partial match
prevents

Access control policy reduces spoofing opportunities but does not prescribe authentication mechanisms.

A.5.16 Identity management partial match
prevents

Identity management supports unique identities but does not guarantee resistance to spoofing.

A.5.18 Access rights partial match
prevents

Access rights assignment limits exposure but does not enforce authentication strength.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248827 OL 8 must not have the rsh-server package installed. prevents CWE-290
RHEL 7 (1 rule)
  • V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. prevents CWE-290
RHEL 8 (1 rule)
  • V-230492 RHEL 8 must not have the rsh-server package installed. prevents CWE-290

References