What is CVE-2021-24857?

CVE-2021-24857 is a critical-severity vulnerability in Nocean Totop Link, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2021-12-13.

How severe is CVE-2021-24857?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2021-24857 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Deserialization in Nocean Totop Link

CVE-2021-24857

The ToTop Link WordPress plugin through 1.7.1 passes base64 encoded user input to the unserialize() PHP function, which could lead to PHP Object injection if a plugin installed on the blog has a suitable gadget chain.

Vulnerability class: Insecure Deserialization

Published 2021-12-13 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.019 (79.1th percentile), scored 2026-10-08.

Low probability of exploitation in the next 30 days, but still tracked. 79th percentile — 79.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.018 · newest: 0.019 · change: +0.001

Affected products

Nocean Totop Link
Totop Link — versions 1.7.1

Weakness classification (CWE)

CWE-502 — Deserialization of Untrusted Data

Public proof-of-concept exploits

20142995/nuclei-templates

References

wpscan.com/vulnerability/518204d8-fbf5-4bfa-9db5-835f908f8d8e (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-24857?: CVE-2021-24857 is a critical-severity vulnerability in Nocean Totop Link, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2021-12-13.
How severe is CVE-2021-24857?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2021-24857 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.