What is CVE-2021-36888?

CVE-2021-36888 is a critical-severity vulnerability in Blocksera Image Hover Effects, classified under Improper Access Control. CVSS score: 9.8/10. Published 2021-12-15.

How severe is CVE-2021-36888?

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

Is CVE-2021-36888 known to be exploited?

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

Auth bypass in Blocksera Image Hover Effects

CVE-2021-36888

Unauthenticated Arbitrary Options Update vulnerability leading to full website compromise discovered in Image Hover Effects Ultimate (versions <= 9.6.1) WordPress plugin.

Published 2021-12-15 · 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: 0.067 (93.7th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 94th percentile — 93.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.067 · newest: 0.067 · change: -0.001

Affected products

Blocksera Image Hover Effects
Oxilab Image Hover Effects Ultimate (WordPress Plugin) — versions <= 9.6.1

Weakness classification (CWE)

Public proof-of-concept exploits

20142995/nuclei-templates

References

wordpress.org/plugins/image-hover-effects-ultimate/ (Release Notes, Vendor Advisory)
patchstack.com/database/vulnerability/image-hover-effects-ultimate/wordpress-im… (Third Party Advisory)

Frequently asked questions

What is CVE-2021-36888?: CVE-2021-36888 is a critical-severity vulnerability in Blocksera Image Hover Effects, classified under Improper Access Control. CVSS score: 9.8/10. Published 2021-12-15.
How severe is CVE-2021-36888?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2021-36888 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.