What is CVE-2015-1555?

CVE-2015-1555 is a critical-severity vulnerability in Zend Framework, classified under Improper Input Validation. CVSS score: 9.1/10. Published 2017-08-07.

How severe is CVE-2015-1555?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Improper input validation in Zend Framework

CVE-2015-1555

Zend/Session/SessionManager in Zend Framework 2.2.x before 2.2.9, 2.3.x before 2.3.4 allows remote attackers to create valid sessions without using session validators.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published 2017-08-07 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.014 (71.3th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 71st percentile — 71.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: 0.000

Affected products

Zend Framework — versions 2.2.0, 2.2.1, 2.2.2

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

framework.zend.com/security/advisory/ZF2015-01 (Vendor Advisory)

Frequently asked questions

What is CVE-2015-1555?: CVE-2015-1555 is a critical-severity vulnerability in Zend Framework, classified under Improper Input Validation. CVSS score: 9.1/10. Published 2017-08-07.
How severe is CVE-2015-1555?: Critical severity. CVSS v3 base score is 9.1 out of 10.