CVE-2026-33409 [High] | Authentication Bypass in Parse-Server

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.52 and 9.6.0-alpha.41, an authentication bypass vulnerability allows an attacker to log in as any user who has linked a third-party authentication provider, without knowing the user's credentials. The attacker only needs to know the user's provider ID to gain full access to their account, including a valid session token. This affects Parse Server deployments where the server option allowExpiredAuthDataToken is set to true. The default value is false. This issue has been patched in versions 8.6.52 and 9.6.0-alpha.41.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-21	0.05%	0.02%	-0.03%
2	2026-03-30	0.04%	0.05%	+0.01%
3	2026-03-26	—	0.04%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-21

0.05%

0.02%

-0.03%

2026-03-30

0.04%

0.05%

+0.01%

2026-03-26

—

0.04%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.0	4.0	HIGH	`CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:A/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` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network. Attack complexity (AC:H) Exploitation depends on constrained or hard-to-reproduce conditions. Attack requirements (AT:P) Additional preconditions must be present for exploitation. Privileges required (PR:H) High privileges are required. User interaction (UI:A) User interaction is required in an active way. Vulnerable system confidentiality impact (VC:H) High confidentiality impact on the vulnerable system. Vulnerable system integrity impact (VI:H) High integrity impact on the vulnerable system. Vulnerable system availability impact (VA:N) No availability impact on the vulnerable system. Subsequent system confidentiality impact (SC:N) No confidentiality impact on subsequent systems. Subsequent system integrity impact (SI:N) No integrity impact on subsequent systems. Subsequent system availability impact (SA:N) No availability impact on subsequent systems. Exploit maturity (threat) (E:X) Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked). Confidentiality requirement (CR:X) Not defined: insufficient information; scoring treats this like High (worst case). Integrity requirement (IR:X) Not defined: insufficient information; scoring treats this like High (worst case). Availability requirement (AR:X) Not defined: insufficient information; scoring treats this like High (worst case). Modified attack vector (MAV:X) Not defined: scoring uses the Base Attack Vector (AV). Modified attack complexity (MAC:X) Not defined: scoring uses the Base Attack Complexity (AC). Modified attack requirements (MAT:X) Not defined: scoring uses the Base Attack Requirements (AT). Modified privileges required (MPR:X) Not defined: scoring uses the Base Privileges Required (PR). Modified user interaction (MUI:X) Not defined: scoring uses the Base User Interaction (UI). Modified vulnerable system confidentiality impact (MVC:X) Not defined: scoring uses the Base VC metric. Modified vulnerable system integrity impact (MVI:X) Not defined: scoring uses the Base VI metric. Modified vulnerable system availability impact (MVA:X) Not defined: scoring uses the Base VA metric. Modified subsequent system confidentiality impact (MSC:X) Not defined: scoring uses the Base SC metric. Modified subsequent system integrity impact (MSI:X) Not defined: scoring uses the Base SI metric. Modified subsequent system availability impact (MSA:X) Not defined: scoring uses the Base SA metric. Safety (supplemental) (S:X) Not evaluated. Automatable (supplemental) (AU:X) Not evaluated. Recovery (supplemental) (R:X) Not evaluated. Value density (supplemental) (V:X) Not evaluated. Vulnerability response effort (supplemental) (RE:X) Not evaluated. Provider urgency (supplemental) (U:X) Not evaluated.	—	—	[email protected]
9.1	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.	3.9	5.2	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.0

4.0

HIGH

CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:A/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

Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network.
Attack complexity (AC:H): Exploitation depends on constrained or hard-to-reproduce conditions.
Attack requirements (AT:P): Additional preconditions must be present for exploitation.
Privileges required (PR:H): High privileges are required.
User interaction (UI:A): User interaction is required in an active way.
Vulnerable system confidentiality impact (VC:H): High confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:H): High integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:N): No availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N): No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N): No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N): No availability impact on subsequent systems.
Exploit maturity (threat) (E:X): Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X): Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X): Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X): Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X): Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X): Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X): Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X): Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X): Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X): Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X): Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X): Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X): Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X): Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X): Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X): Not evaluated.
Automatable (supplemental) (AU:X): Not evaluated.
Recovery (supplemental) (R:X): Not evaluated.
Value density (supplemental) (V:X): Not evaluated.
Vulnerability response effort (supplemental) (RE:X): Not evaluated.
Provider urgency (supplemental) (U:X): Not evaluated.

—

[email protected]

9.1

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N): Service keeps running; no real outage angle.

3.9

5.2

[email protected]

Affected software / configurations for CVE-2026-33409

Vendor	Product	Version	Raw CPE
parseplatform	parse-server	< 8.6.52	cpe:2.3:a:parseplatform:parse-server::::::node.js::*
parseplatform	parse-server	>= 9.0.0, < 9.6.0	cpe:2.3:a:parseplatform:parse-server::::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha1::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha10::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha11::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha12::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha13::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha14::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha15::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha16::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha17::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha18::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha19::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha2::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha20::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha21::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha22::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha23::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha24::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha25::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha26::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha27::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha28::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha29::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha3::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha30::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha31::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha32::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha33::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha34::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha35::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha36::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha37::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha38::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha39::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha4::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha40::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha5::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha6::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha7::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha8::::node.js::*
parseplatform	parse-server	9.6.0	cpe:2.3:a:parseplatform:parse-server:9.6.0:alpha9::::node.js::*

References for CVE-2026-33409

URL	Tags
https://github.com/parse-community/parse-server/commit/8d7df5639c4a35768fe8b78b4580b30e8a74721c	Patch
https://github.com/parse-community/parse-server/commit/98f4ba5bcf2c199bfe6225f672e8edcd08ba732d	Patch
https://github.com/parse-community/parse-server/pull/10246	Issue Tracking
https://github.com/parse-community/parse-server/pull/10247	Issue Tracking
https://github.com/parse-community/parse-server/security/advisories/GHSA-pfj7-wv7c-22pr	Vendor Advisory

URL

CVE-2026-33409 | Parse Server: Auth provider validation bypass on login via partial authData

Exploit prediction scoring system (EPSS) score for CVE-2026-33409

Common vulnerability scoring system (CVSS) metrics for CVE-2026-33409

Weakness enumeration for CVE-2026-33409

GitHub Security Advisory for CVE-2026-33409

Affected software / configurations for CVE-2026-33409

References for CVE-2026-33409