How severe is CVE-2026-34373?

No CVSS score has been assigned to CVE-2026-34373 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-34373?

CVE-2026-34373 affects the following packages: parse-server (npm), parse-server (npm). Ecosystems affected: npm.

How do I fix CVE-2026-34373?

Update parse-server to 9.7.0-alpha.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34373 is resolved across your whole dependency graph.

How do I detect CVE-2026-34373 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for parse-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-34373 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-34373 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-34373 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-34373?

CVE-2026-34373 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 11th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-34373?

CVE-2026-34373 is classified as CWE-346 (CWE-346). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-34373 published, and has it been updated?

CVE-2026-34373 was published on March 31, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

Not in CISA KEV

CVE-2026-34373 — parse-server

Fix: parse-community/parse-server@0347641

CVE-2026-34373 is a CWE-346 vulnerability in parse-server. A fix is available for parse-server — see the affected versions and patch details below.

Parse Server: GraphQL API endpoint ignores CORS origin restriction

Also known asBIT-parse-2026-34373GHSA-q3p6-g7c4-829c

Published

Mar 31, 2026

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-34373.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk-0.04%

Lower risk than most CVEs11th percentile — riskier than 11% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

62other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

parse-servernpm

65Kdownloads / week

Description

Impact

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.

Patches

The GraphQL API endpoint now uses the same CORS middleware as the REST API, ensuring the allowOrigin and allowHeaders server options are consistently enforced across all endpoints.

Workarounds

There is no known workaround other than upgrading.

Resources

GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-q3p6-g7c4-829c
Fix Parse Server 9: https://github.com/parse-community/parse-server/pull/10334
Fix Parse Server 8: https://github.com/parse-community/parse-server/pull/10335

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`parse-server`	≥ 9.0.0&&< 9.7.0-alpha.10	9.7.0-alpha.10`npm install parse-server@9.7.0-alpha.10`
📦npm	`parse-server`	≥ 3.5.0&&< 8.6.66	8.6.66`npm install parse-server@8.6.66`

Affected Products

1 product · 11 configurations

Application

parse-serverparseplatform

≥ 9.0.0 && < 9.7.0

1 version

9.7.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for parse-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update parse-server to 9.7.0-alpha.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34373 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Impact 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. ### Patches The GraphQL API endpoint now uses the same CORS middleware as the REST API, ensuring the `allowOrigin` and `allowHeaders` server options are consistently enforced across all endpoints. ### Workarounds There is no known workaround ot

O3 Security · Impact-Aware SCA

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