What is CVE-2020-8986?

CVE-2020-8986 is a critical-severity vulnerability in Zend Zendto, classified under Improper Check for Unusual or Exceptional Conditions. CVSS score: 9.8/10. Published 2020-03-24.

How severe is CVE-2020-8986?

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

Vulnerability in Zend Zendto

CVE-2020-8986

lib/NSSDropbox.php in ZendTo prior to 5.22-2 Beta failed to properly check for equality when validating the session cookie, allowing an attacker to gain administrative access with a large number of requests.

Published 2020-03-24 · 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: 0.015 (73.9th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 74th percentile — 73.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.015 · newest: 0.015 · change: 0.000

Affected products

Zend Zendto — versions 3.10, 3.11, 3.12

Weakness classification (CWE)

CWE-754 — Improper Check for Unusual or Exceptional Conditions

References

zend.to/changelog.php (Release Notes, Vendor Advisory)

Frequently asked questions

What is CVE-2020-8986?: CVE-2020-8986 is a critical-severity vulnerability in Zend Zendto, classified under Improper Check for Unusual or Exceptional Conditions. CVSS score: 9.8/10. Published 2020-03-24.
How severe is CVE-2020-8986?: Critical severity. CVSS v3 base score is 9.8 out of 10.