VulnerabilityPublished 31 Mar 2026

CVE-2026-34373: parse-server · Origin Validation Error

Affects parse-serverSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium : upgrade to 9.7.0-alpha.10 or 8.6.66 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 9.7.0-alpha.10, 8.6.66

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

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: Passive
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: Low
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: Passive: Successful exploitation of this vulnerability requires limited interaction by the targeted user with the vulnerable system and the attacker’s payload. These interactions would be considered involuntary and do not require that the user actively subvert protections built into the vulnerable system.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Subsequent System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 31 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade parse-server to 9.7.0-alpha.10 or 8.6.66; parse-community/parse-server to 8.6.66.

Affected software

Product	Affected	Fixed in
parse-communityparse-server	Affected >=9.0.0 <9.7.0-alpha.10	Fixed in 9.7.0-alpha.10
parse-communityparse-server	Affected <8.6.66	Fixed in 8.6.66
npmparse-community/parse-server`pkg:npm/parse-community/parse-server`Other threats	Affected <8.6.66	Fixed in 8.6.66

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade parse-server instances to version 8.6.66 or later, or 9.7.0-alpha.10 or later, where the vulnerability is patched.
Review and enforce strict CORS policies on the server side, ensuring that only trusted origins are allowed to interact with the GraphQL API.
Implement Content Security Policy (CSP) headers on client applications to restrict the domains that can execute scripts and make cross-origin requests.
Monitor and audit GraphQL API usage logs for unusual cross-origin requests or suspicious activity.
Educate users about the risks of visiting untrusted websites while authenticated to sensitive services.
If upgrading immediately is not possible, consider disabling the GraphQL API endpoint or restricting its network exposure until patched.
Employ web application firewalls (WAFs) that can detect and block suspicious cross-origin requests targeting the GraphQL endpoint.
Conduct regular security assessments and penetration testing focusing on CORS and API endpoint configurations.

Description

Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to versions 8.6.66 and 9.7.0-alpha.10, the GraphQL API endpoint does not respect the allowOrigin server option and unconditionally allows cross-origin requests from any website. This bypasses origin restrictions that operators configure to control which websites can interact with the Parse Server API. The REST API correctly enforces the configured allowOrigin restriction. This issue has been patched in versions 8.6.66 and 9.7.0-alpha.10.

Impact

The primary impact of this vulnerability is the potential for unauthorized cross-origin interactions with the parse-server GraphQL API. Attackers can exploit this to perform actions or retrieve data on behalf of authenticated users if those users visit a malicious website. This can lead to data leakage, unauthorized data modification, or other unintended API interactions. Organizations relying on parse-server for backend services, especially those exposing GraphQL APIs to web clients, risk compromising the confidentiality and integrity of their data. The vulnerability does not affect availability directly but can undermine trust and security posture. Since the REST API is unaffected, the impact is limited to GraphQL API consumers. The ease of exploitation combined with the widespread use of parse-server in various industries including startups, mobile app backends, and web services means a broad range of organizations could be affected if they have not applied patches. The lack of authentication requirement lowers the barrier for exploitation, increasing risk. However, the need for user interaction (victim visiting a malicious site) somewhat limits large-scale automated exploitation.

CWE-346Origin Validation Error (opens in a new tab)
Class weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product does not properly verify that the source of data or communication is valid.
OWASP Cheat Sheets
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V14.5.2 (opens in a new tab)
V14.5.3 (opens in a new tab)
V1.4.4 (opens in a new tab)
Attack patterns
JSON Hijacking (aka JavaScript Hijacking) (opens in a new tab)
Cache Poisoning (opens in a new tab)
DNS Cache Poisoning (opens in a new tab)
Exploit Script-Based APIs (opens in a new tab)
Application API Message Manipulation via Man-in-the-Middle (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 31 Mar 2026, 15:09 UTC

WeaknessesCWE-346

Technical details

References

Community reviews

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