Highly exploitable, CVE-2026-87803 poses a critical security risk that could lead to severe breaches.
Status: Deferred
Published on: 10 Sep 2026, 10:17 UTC
CVSS Release: version 3
report@snyk.io
Secondary
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
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.
The exploitability of CVE-2026-87803 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
CVE-2026-87803 presents an accessible attack vector with minimal effort required. Restricting access controls and implementing security updates are critical to reducing exploitation risks.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2026-87803, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2026-87803, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
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