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CVE-2026-87803

HIGHCVSS 7.1/10EPSS 0.31%

Last modified

CVE-2026-87803 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. An authorization bypass vulnerability exists in the Countly Server DBViewer due to flawed sub-pipeline detection in the aggregation stage sanitizer. The /o/db aggregation endpoint parses user-controlled aggregation JSON and passes it through a stage sanitizer that determines whether a nested array is a sub-pipeline by checking if every element contains a key present in a hardcoded KNOWN_STAGE_OPERATORS set. EPSS estimates a 0.31% chance of exploitation in the next 30 days.

Description

An authorization bypass vulnerability exists in the Countly Server DBViewer due to flawed sub-pipeline detection in the aggregation stage sanitizer. The /o/db aggregation endpoint parses user-controlled aggregation JSON and passes it through a stage sanitizer that determines whether a nested array is a sub-pipeline by checking if every element contains a key present in a hardcoded KNOWN_STAGE_OPERATORS set. If any element contains an unrecognized stage key, such as the undocumented MongoDB-internal $_internalInhibitOptimization, the sanitizer misclassifies the entire branch as a generic array and skips stage-level stripping for all sibling stages. This allows a non-admin user with DBViewer read permission to inject forbidden operators like $lookup inside $facet sub-pipelines, performing cross-collection joins into restricted collections. This leads to unauthorized read access to sensitive data including password-reset tokens (prid), enabling account takeover.

Metrics

CVSS 3.1
7.1/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

CVSS 4.0
7.1/10

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability
0.31%

23.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
Countlycountly-server< 25.03.53-LTS

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-87803?
An authorization bypass vulnerability exists in the Countly Server DBViewer due to flawed sub-pipeline detection in the aggregation stage sanitizer. The /o/db aggregation endpoint parses user-controlled aggregation JSON and passes it through a stage sanitizer that determines whether a nested array is a sub-pipeline by checking if every element contains a key present in a hardcoded KNOWN_STAGE_OPERATORS set. If any element contains an unrecognized stage key, such as the undocumented MongoDB-internal $_internalInhibitOptimization, the sanitizer misclassifies the entire branch as a generic array and skips stage-level stripping for all sibling stages. This allows a non-admin user with DBViewer read permission to inject forbidden operators like $lookup inside $facet sub-pipelines, performing cross-collection joins into restricted collections. This leads to unauthorized read access to sensitive data including password-reset tokens (prid), enabling account takeover.
How severe is CVE-2026-87803?
CVE-2026-87803 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 0.31% probability of exploitation in the next 30 days.
How do I fix CVE-2026-87803?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST