EUVD-2026-35864
GHSA-7r4j-g3f5-3629
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/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
Primary rating from Vendor (mongodb) · only source for this CVE.
CVSS VectorVendor: mongodb
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/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
Lifecycle Timeline
7DescriptionCVE.org
The $_internalConvertBucketIndexStats stage used PauseExecution as a way to signal "skip this document" when an index stats conversion failed. But PauseExecution is not a general purpose skip mechanism, but rather a TeeBuffer-internal signal used solely by $facet to coordinate its sub-pipelines. When this stage is placed before $facet in a pipeline, TeeBuffer receives the unexpected PauseExecution from upstream and hits a hard invariant assertion, crashing mongod.
AnalysisAI
Remote denial-of-service in MongoDB Server allows an authenticated user to crash the mongod process by submitting an aggregation pipeline that places the $_internalConvertBucketIndexStats stage upstream of a $facet stage. The misuse of the internal PauseExecution signal trips a hard invariant assertion in TeeBuffer, terminating the database process. No public exploit identified at time of analysis, and the issue is tracked in MongoDB's internal tracker SERVER-123951.
Technical ContextAI
MongoDB's aggregation framework uses internal control signals to coordinate stage execution. PauseExecution is a TeeBuffer-internal signal that $facet relies on to multiplex its sub-pipelines from a single input stream - it is not a general-purpose 'skip document' mechanism. The $_internalConvertBucketIndexStats stage, used in time-series index statistics conversion, incorrectly reused PauseExecution to indicate that an index stats conversion had failed and the document should be skipped. When such a stage feeds into $facet, TeeBuffer receives the unexpected signal from upstream rather than from its own coordination logic and triggers a fatal invariant assertion. This maps to CWE-617 (Reachable Assertion): a code path the developer assumed unreachable becomes reachable through crafted input, and tripping the invariant aborts mongod rather than returning an error to the client.
RemediationAI
Patch status not confirmed from available data - consult the MongoDB advisory at https://jira.mongodb.org/browse/SERVER-123951 for the fixed release train and apply the corresponding upgrade once published. As a compensating control until patched, restrict who can execute arbitrary aggregation pipelines: review built-in and custom roles to ensure that application accounts do not hold broader privileges than required (revoke read on collections that do not need aggregation, and avoid granting roles that permit time-series internal stages to untrusted callers); the trade-off is operational friction if applications rely on broad roles. At the application layer, validate or whitelist aggregation pipelines submitted by end users so that $_internalConvertBucketIndexStats cannot be introduced from untrusted input, accepting that this requires server-side query review. Configure replica sets with monitoring and automatic restart so an exploited crash recovers quickly, and ensure backups are current to bound impact if cascading restarts occur.
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Same weakness CWE-617 – Reachable Assertion
View allSame technique Denial Of Service
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External POC / Exploit Code
Leaving vuln.today