CVE-2020-5251Public exploitNetwork attack vector

Unauthenticated account takeover via regex token queries

Published Mar 4, 2020 · Updated Aug 4, 2024

Incorrect authorization in Parse Platform Parse Server before 4.1.0 allows remote attackers to discover valid accounts through crafted NoSQL queries. Session-token middleware and public email-verification and password-reset handlers accept object-valued token input, allowing a supplied $regex operator to reach database comparisons instead of enforcing an exact string token. No prior authentication or user interaction is required; repeated matches disclose user objects and enable account verification or password reset for another username.

CVSS severity7.7
High
EPSS probability0.85%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Parse Platform Parse Server before 4.1.0 allows remote attackers to discover valid accounts through crafted NoSQL queries. Session-token middleware and public email-verification and password-reset handlers accept object-valued token input, allowing a supplied $regex operator to reach database comparisons instead of enforcing an exact string token. No prior authentication or user interaction is required; repeated matches disclose user objects and enable account verification or password reset for another username.

The record

CVE
CVE-2020-5251
Published
Mar 4, 2020
Updated
Aug 4, 2024
Vendor
Parse Platform
Product
Parse Server
Classifications
CWE-863, CWE-285, T1528
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 4, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Parse Platform · Parse Serverversion=< 4.1.0

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
7.7GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-863Incorrect Authorization
CWE-285Improper Authorization
T1528Steal Application Access Token

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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