CVE-2026-49252 is a critical-severity (CVSS 9.9) CWE-1321 vulnerability in @deepstream/server. A fix is available for @deepstream/server — see the affected versions and patch details below.
deepstream is vulnerable to prototype pollution
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-49252.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-49252 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@deepstream/servernpmDescription
deepstream is a server that allows clients and backend services to sync data, send messages and make rpcs at scale. Versions prior to 10.0.5 are vulnerable to Prototype Pollution. Exploitation can lead to potential privilege escalation from any authenticated user with write permission to any record. This issue has been fixed in version 10.0.5.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @deepstream/server | all versions | 10.0.5npm install @deepstream/server@10.0.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @deepstream/server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @deepstream/server to 10.0.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49252 is resolved across your whole dependency graph.
Workarounds
Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.
Frequently Asked Questions
Is CVE-2026-49252 in your dependencies?
Find it across npm, including transitive dependencies.