CVE-2026-87803Network attack vector

Account takeover via nested aggregation sanitizer bypass

Published Sep 10, 2026 · Updated Sep 10, 2026

Authorization bypass in Countly Server before 25.03.53-LTS allows remote authenticated users to read restricted data through DBViewer. The /o/db aggregation sanitizer treats a nested array as generic when one element uses an operator absent from its hardcoded set, skipping stage stripping for sibling $lookup stages. DBViewer read permission is required; joins into password_reset expose reset tokens that permit takeover of affected accounts.

CVSS severityUnavailable
Unscored
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in Countly Server before 25.03.53-LTS allows remote authenticated users to read restricted data through DBViewer. The /o/db aggregation sanitizer treats a nested array as generic when one element uses an operator absent from its hardcoded set, skipping stage stripping for sibling $lookup stages. DBViewer read permission is required; joins into password_reset expose reset tokens that permit takeover of affected accounts.

The record

CVE
CVE-2026-87803
Published
Sep 10, 2026
Updated
Sep 10, 2026
Vendor
Countly
Product
Countly Server
Classifications
T1213
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 10, 2026Record 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=0 <25.03.53-LTS

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Countly · Countly Serverversion=0 <25.03.53-LTS

Published CVSS scores

No CVSS assessment is available in this record.

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1213Data from Information Repositories

Public exploit references

No public exploit references are available in this record.

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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