CVE-2022-2421 | Socket.io - Improper type validation in attachment parsing

Due to improper type validation in attachment parsing the Socket.io js library, it is possible to overwrite the _placeholder object which allows an attacker to place references to functions at arbitrary places in the resulting query object.

Published: 2022-10-26 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2022-2421 is rated Moderate Risk (62/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 1.12%). 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-2022-2421

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 2026-06-15 0.76% 1.12% +0.36%
2 2026-05-11 1.03% 0.76% -0.27%
3 2026-05-09 — 1.03% —

Full EPSS history (51 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2022-2421

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
10.0 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/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:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 6.0 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]

Weakness enumeration for CVE-2022-2421

GitHub Security Advisory for CVE-2022-2421

GHSA-qm95-pgcg-qqfq · Severity: critical · Ecosystem: npm — Insufficient validation when decoding a Socket.IO packet

Affected software / configurations for CVE-2022-2421

Vendor Product Version Raw CPE
socket socket.io-parser < 3.3.3 cpe:2.3:a:socket:socket.io-parser:*:*:*:*:*:node.js:*:*
socket socket.io-parser >= 3.4.0, < 3.4.2 cpe:2.3:a:socket:socket.io-parser:*:*:*:*:*:node.js:*:*
socket socket.io-parser >= 4.0.0, < 4.0.5 cpe:2.3:a:socket:socket.io-parser:*:*:*:*:*:node.js:*:*
socket socket.io-parser >= 4.1.0, < 4.2.1 cpe:2.3:a:socket:socket.io-parser:*:*:*:*:*:node.js:*:*

References for CVE-2022-2421

URL Tags
https://csirt.divd.nl/CVE-2022-2421 Third Party Advisory
https://csirt.divd.nl/DIVD-2022-00045 Third Party Advisory
cvelogic Threat Intelligence