CVE-2026-34573 [High] | Denial of Service 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 8.6.68 and 9.7.0-alpha.12, the GraphQL query complexity validator can be exploited to cause a denial-of-service by sending a crafted query with binary fan-out fragment spreads. A single unauthenticated request can block the Node.js event loop for seconds, denying service to all concurrent users. This only affects deployments that have enabled the requestComplexity.graphQLDepth or requestComplexity.graphQLFields configuration options. This issue has been patched in versions 8.6.68 and 9.7.0-alpha.12.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-05-22	0.05%	0.02%	-0.03%
2	2026-04-06	0.04%	0.05%	+0.01%
3	2026-04-01	—	0.04%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-05-22

0.05%

0.02%

-0.03%

2026-04-06

0.04%

0.05%

+0.01%

2026-04-01

—

0.04%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.2	4.0	HIGH	`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/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:L) Exploitation conditions are straightforward and stable. Attack requirements (AT:P) Additional preconditions must be present for exploitation. Privileges required (PR:N) No privileges are required. User interaction (UI:N) No user interaction is required. Vulnerable system confidentiality impact (VC:N) No confidentiality impact on the vulnerable system. Vulnerable system integrity impact (VI:N) No integrity impact on the vulnerable system. Vulnerable system availability impact (VA:H) High 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]
7.5	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` 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:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	3.6	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.2

4.0

HIGH

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/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:L): Exploitation conditions are straightforward and stable.
Attack requirements (AT:P): Additional preconditions must be present for exploitation.
Privileges required (PR:N): No privileges are required.
User interaction (UI:N): No user interaction is required.
Vulnerable system confidentiality impact (VC:N): No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N): No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:H): High 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]

7.5

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H 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:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

3.6

[email protected]

Affected software / configurations for CVE-2026-34573

Vendor	Product	Version	Raw CPE
parseplatform	parse-server	< 8.6.68	cpe:2.3:a:parseplatform:parse-server::::::node.js::*
parseplatform	parse-server	>= 9.0.0, < 9.7.0	cpe:2.3:a:parseplatform:parse-server::::::node.js::*
parseplatform	parse-server	9.7.0	cpe:2.3:a:parseplatform:parse-server:9.7.0:alpha1::::node.js::*
parseplatform	parse-server	9.7.0	cpe:2.3:a:parseplatform:parse-server:9.7.0:alpha10::::node.js::*
parseplatform	parse-server	9.7.0	cpe:2.3:a:parseplatform:parse-server:9.7.0:alpha11::::node.js::*
parseplatform	parse-server	9.7.0	cpe:2.3:a:parseplatform:parse-server:9.7.0:alpha2::::node.js::*
parseplatform	parse-server	9.7.0	cpe:2.3:a:parseplatform:parse-server:9.7.0:alpha3::::node.js::*
parseplatform	parse-server	9.7.0	cpe:2.3:a:parseplatform:parse-server:9.7.0:alpha4::::node.js::*
parseplatform	parse-server	9.7.0	cpe:2.3:a:parseplatform:parse-server:9.7.0:alpha5::::node.js::*
parseplatform	parse-server	9.7.0	cpe:2.3:a:parseplatform:parse-server:9.7.0:alpha6::::node.js::*
parseplatform	parse-server	9.7.0	cpe:2.3:a:parseplatform:parse-server:9.7.0:alpha7::::node.js::*
parseplatform	parse-server	9.7.0	cpe:2.3:a:parseplatform:parse-server:9.7.0:alpha8::::node.js::*
parseplatform	parse-server	9.7.0	cpe:2.3:a:parseplatform:parse-server:9.7.0:alpha9::::node.js::*

References for CVE-2026-34573

URL	Tags
https://github.com/parse-community/parse-server/commit/ea15412795f34594cc8a674fe858d445675e0295	Patch
https://github.com/parse-community/parse-server/commit/f759bda075298ec44e2b4fb57659a0c56620483b	Patch
https://github.com/parse-community/parse-server/pull/10344	Issue Tracking Patch
https://github.com/parse-community/parse-server/pull/10345	Issue Tracking Patch
https://github.com/parse-community/parse-server/security/advisories/GHSA-mfj6-6p54-m98c	Patch Vendor Advisory

URL

CVE-2026-34573 | Parse Server: GraphQL complexity validator exponential fragment traversal DoS

Exploit prediction scoring system (EPSS) score for CVE-2026-34573

Common vulnerability scoring system (CVSS) metrics for CVE-2026-34573

Weakness enumeration for CVE-2026-34573

GitHub Security Advisory for CVE-2026-34573

Affected software / configurations for CVE-2026-34573

References for CVE-2026-34573