No exploitation reportedFix available

CVE-2022-2421

Q: Is CVE-2022-2421 actively exploited?

Active exploitation of CVE-2022-2421 has not been confirmed. Its EPSS score was 1.6% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2022-2421?

CVE-2022-2421 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2022-10-26
Fixed in4.2.1 · 4.0.5 · 3.4.2 · 3.3.3
WeaknessCWE-89

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC

2022-10-2610:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2022-2421?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2022-2421?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Socket socket.io-parser

Branch	Affected	Fixed in	Source
4.x	≥ 4.1.0, < 4.2.1	4.2.1	NVD
4.0	≥ 4.0.0, < 4.0.5	4.0.5	NVD
3.4	≥ 3.4.0, < 3.4.2	3.4.2	NVD
3.3	< 3.3.3	3.3.3	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Socket socket.io-parser to 4.2.1 · 4.0.5 · 3.4.2 · 3.3.3

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CISA-ADPSSVC decisionnone2024-11-20
OpenCVESSVC decisionnone—
CNACVSS 3.110read 2026-10-23
NVDCVSS 3.19.8read 2026-10-23
CNAweakness (CWE)CWE-89read 2026-10-23
FIRST EPSSEPSS score1.6 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2022-10-26
Last Modified: 2026-06-17
NVD status: Analyzed

Frequently asked questions

What is CVE-2022-2421?

Is CVE-2022-2421 actively exploited?

Active exploitation of CVE-2022-2421 has not been confirmed. Its EPSS score was 1.6% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2022-2421?

CVE-2022-2421 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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