CVE-2022-21676 | Uncaught Exception in engine.io

Engine.IO is the implementation of transport-based cross-browser/cross-device bi-directional communication layer for Socket.IO. A specially crafted HTTP request can trigger an uncaught exception on the Engine.IO server, thus killing the Node.js process. This impacts all the users of the `engine.io` package starting from version `4.0.0`, including those who uses depending packages like `socket.io`. Versions prior to `4.0.0` are not impacted. A fix has been released for each major branch, namely `4.1.2` for the `4.x.x` branch, `5.2.1` for the `5.x.x` branch, and `6.1.1` for the `6.x.x` branch. There is no known workaround except upgrading to a safe version.

Published: 2022-01-12 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2022-21676 is rated Moderate Risk (59.1/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.76%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2022-21676

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-21 3.18% 2.76% -0.42%
2 2026-06-15 4.08% 3.18% -0.91%
3 2025-11-21 — 4.08% —

Full EPSS history (17 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2022-21676

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2022-21676

GitHub Security Advisory for CVE-2022-21676

Affected software / configurations for CVE-2022-21676

Vendor Product Version Raw CPE
socket engine.io >= 4.0.0, < 4.1.2 cpe:2.3:a:socket:engine.io:*:*:*:*:*:node.js:*:*
socket engine.io >= 5.0.0, < 5.2.1 cpe:2.3:a:socket:engine.io:*:*:*:*:*:node.js:*:*
socket engine.io >= 6.0.0, < 6.1.1 cpe:2.3:a:socket:engine.io:*:*:*:*:*:node.js:*:*

References for CVE-2022-21676

URL Tags
https://github.com/socketio/engine.io/commit/66f889fc1d966bf5bfa0de1939069153643874ab Patch Third Party Advisory
https://github.com/socketio/engine.io/commit/a70800d7e96da32f6e6622804ef659ebc58659db Patch Third Party Advisory
https://github.com/socketio/engine.io/commit/c0e194d44933bd83bf9a4b126fca68ba7bf5098c Patch Third Party Advisory
https://github.com/socketio/engine.io/releases/tag/4.1.2 Release Notes Third Party Advisory
https://github.com/socketio/engine.io/releases/tag/5.2.1 Release Notes Third Party Advisory
https://github.com/socketio/engine.io/releases/tag/6.1.1 Release Notes Third Party Advisory
https://github.com/socketio/engine.io/security/advisories/GHSA-273r-mgr4-v34f Third Party Advisory
https://security.netapp.com/advisory/ntap-20220209-0002/ Third Party Advisory
cvelogic Threat Intelligence