How severe is CVE-2015-1555?

CVE-2015-1555 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2015-1555 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (69th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-1555?

CVE-2015-1555 primarily affects Zend Zend Framework. In total, 13 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2015-1555?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2015-1555 published?

CVE-2015-1555 was published on 2017-08-07 and last updated on 2026-06-17.

CVE-2015-1555

CVE-2015-1555 is a critical-severity vulnerability in Zend Zend Framework with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v2: 6.4
EPSS exploit prediction: 1% (69th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Zend Zend Framework
Published: 2017-08-07
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2015-1555?: CVE-2015-1555 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2015-1555 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (69th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2015-1555?: CVE-2015-1555 primarily affects Zend Zend Framework. In total, 13 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2015-1555?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2015-1555 published?: CVE-2015-1555 was published on 2017-08-07 and last updated on 2026-06-17.

References

http://framework.zend.com/security/advisory/ZF2015-01

Affected products (13)

cpe:2.3:a:zend:zend_framework:2.2.0:*:*:*:*:*:*:*
cpe:2.3:a:zend:zend_framework:2.2.1:*:*:*:*:*:*:*
cpe:2.3:a:zend:zend_framework:2.2.2:*:*:*:*:*:*:*
cpe:2.3:a:zend:zend_framework:2.2.3:*:*:*:*:*:*:*
cpe:2.3:a:zend:zend_framework:2.2.4:*:*:*:*:*:*:*
cpe:2.3:a:zend:zend_framework:2.2.5:*:*:*:*:*:*:*
cpe:2.3:a:zend:zend_framework:2.2.6:*:*:*:*:*:*:*
cpe:2.3:a:zend:zend_framework:2.2.7:*:*:*:*:*:*:*
cpe:2.3:a:zend:zend_framework:2.2.8:*:*:*:*:*:*:*
cpe:2.3:a:zend:zend_framework:2.3.0:*:*:*:*:*:*:*
cpe:2.3:a:zend:zend_framework:2.3.1:*:*:*:*:*:*:*
cpe:2.3:a:zend:zend_framework:2.3.2:*:*:*:*:*:*:*
cpe:2.3:a:zend:zend_framework:2.3.3:*:*:*:*:*:*:*

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