How severe is CVE-2026-31901?

No CVSS score has been assigned to CVE-2026-31901 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-31901?

CVE-2026-31901 affects the following packages: parse-server (npm), parse-server (npm). Ecosystems affected: npm.

How do I fix CVE-2026-31901?

Update parse-server to 9.6.0-alpha.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-31901 is resolved across your whole dependency graph.

How do I detect CVE-2026-31901 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-2026-31901 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-2026-31901 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-31901 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-2026-31901?

CVE-2026-31901 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 17th 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-2026-31901?

CVE-2026-31901 is classified as CWE-204 (CWE-204). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-31901 published, and has it been updated?

CVE-2026-31901 was published on March 11, 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-2026-31901 — parse-server

CVE-2026-31901 is a CWE-204 vulnerability in parse-server. A fix is available for parse-server — see the affected versions and patch details below.

Parse Server has user enumeration via email verification endpoint

Also known asBIT-parse-2026-31901GHSA-w54v-hf9p-8856

Published

Mar 11, 2026

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 31, 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-2026-31901.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs17th percentile — riskier than 17% 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

82Kdownloads / week

Description

Impact

The email verification endpoint (/verificationEmailRequest) returns distinct error responses depending on whether an email address belongs to an existing user, is already verified, or does not exist. An attacker can send requests with different email addresses and observe the error codes to determine which email addresses are registered in the application.

This is a user enumeration vulnerability that affects any Parse Server deployment with email verification enabled (verifyUserEmails: true).

Patches

The fix introduces a new Parse Server option emailVerifySuccessOnInvalidEmail (default: true) that returns a generic success response for all verification email requests, regardless of whether the email address is valid, already verified, or non-existent. This prevents an attacker from distinguishing between these cases.

The fix also strengthens the input validation for the related resetPasswordSuccessOnInvalidEmail option, and adds security checks that warn when either enumeration mitigation is disabled.

Workarounds

There is no known workaround.

References

GitHub security advisory: https://github.com/parse-community/parse-server/security/advisories/GHSA-w54v-hf9p-8856
Fix Parse Server 9: https://github.com/parse-community/parse-server/releases/tag/9.6.0-alpha.8
Fix Parse Server 8: https://github.com/parse-community/parse-server/releases/tag/8.6.34

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`parse-server`	≥ 9.0.0-alpha.1&&< 9.6.0-alpha.8	9.6.0-alpha.8`npm install parse-server@9.6.0-alpha.8`
📦npm	`parse-server`	all versions	8.6.34`npm install parse-server@8.6.34`

Affected Products

1 product · 9 configurations

Application

parse-serverparseplatform

≥ 9.0.0 && < 9.6.0

1 version

9.6.0

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 9.6.0-alpha.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-31901 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 email verification endpoint (`/verificationEmailRequest`) returns distinct error responses depending on whether an email address belongs to an existing user, is already verified, or does not exist. An attacker can send requests with different email addresses and observe the error codes to determine which email addresses are registered in the application. This is a user enumeration vulnerability that affects any Parse Server deployment with email verification enabled (`verifyUserEmails: true`). ### Patches The fix introduces a new Parse Server option `emailVerifySuccessOnInva