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HIGH

CVE-2026-84942

CVE-2026-84942 — Stored Cross-Site Scripting via Vega Expression Function Bypass in OpenSearch Dashboards

Improper input validation in the Vega expression function implementation in OpenSearch Dashboards allows a remote authenticated actor with dashboard write permissions to execute arbitrary JavaScript in the context of other users' browser sessions by saving a crafted Vega visualization. The checkForFunctionProperty validation routine failed to recurse into arrays of objects, allowing a function property nested inside an array to bypass validation.

Published Updated Sources: cvelistV5, AMZN

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

0%

chance of exploitation in 30 days

Affects

aws

2 products listed

CVSS base

8.7

HIGH

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

None

none · proof-of-concept · active

Automatable

No

can an attacker script all four kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Affected scope

The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.

Vendors (2)

awsopensearch

Products (2)

amazon opensearch serviceopensearch dashboards

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactSource
8.7CVSS 3.1HIGH——cvelistV5

Weakness & attack patterns

  • CWE-79

References

3 on the record

Elsewhere on this site

  • awsevery CVE for this vendor
  • opensearchevery CVE for this vendor
  • CWE-79other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.