CVE-2026-102600 json
Socket.IO: Prototype Pollution via Unsafe Client Session Lookup
published last mo. modified last mo. also GHSA-wfpm-5gcm-94cg , EUVD-2026-88981
- cvss
- 7.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 32%
- public exploits
- 0
- none known
Summary
Socket.IO enables bidirectional and low-latency communication for every platform. Prior to 0.1.1, @socket.io/cluster-engine uses inherited object properties when looking up attacker-controlled session IDs in clustered deployments. Special property names such as __proto__ or constructor can resolve through the object prototype chain instead of identifying an actual connected client, causing the Node.js process to crash and resulting in denial of service. Applications that do not use @socket.io/cluster-engine are not affected. This issue is fixed in version 0.1.1.
Patch / fix
- npm @socket.io/cluster-engine 0.1.1
Is CVE-2026-102600 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- last mo.
Exploit prediction
0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| GitHub | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | @socket.io/cluster-engine | <0.1.1 |
0.1.1 |
Affected products
- socketio socket.io
- @socket.io cluster-engine
Classification
References
-
github.com
/socketio/socket.io/commit/830e3642ebb8dc3784eb749b0a004fe2b932b429
web
-
github.com
/socketio/socket.io/security/advisories/GHSA-wfpm-5gcm-94cg
web
-
github.com
/socketio/socket.io/releases/tag/@socket.io/cluster-engine@0.1.1
web
-
nvd.nist.gov
/vuln/detail/CVE-2026-102600
advisory
-
github.com
/socketio/socket.io
package
Sources
- CVE List CVE-2026-102600
- GitHub Advisory GHSA-wfpm-5gcm-94cg
- NVD CVE-2026-102600
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