How severe is CVE-2015-6834?

CVE-2015-6834 has a CVSS 3.x base score of 9.8, 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 high.

Is CVE-2015-6834 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 47% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-6834?

CVE-2015-6834 primarily affects Php. In total, 43 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2015-6834?

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-2015-6834 published?

CVE-2015-6834 was published on 2016-05-16 and last updated on 2026-06-17.

CVE-2015-6834

CVE-2015-6834 is a critical-severity vulnerability in Php with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 47% places it in the 99th percentile, indicating an elevated likelihood of exploitation.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 47% (99th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Php
Published: 2016-05-16
Last modified: 2026-06-17

Description

Multiple use-after-free vulnerabilities in PHP before 5.4.45, 5.5.x before 5.5.29, and 5.6.x before 5.6.13 allow remote attackers to execute arbitrary code via vectors related to (1) the Serializable interface, (2) the SplObjectStorage class, and (3) the SplDoublyLinkedList class, which are mishandled during unserialization.

Frequently asked questions

What is CVE-2015-6834?: Multiple use-after-free vulnerabilities in PHP before 5.4.45, 5.5.x before 5.5.29, and 5.6.x before 5.6.13 allow remote attackers to execute arbitrary code via vectors related to (1) the Serializable interface, (2) the SplObjectStorage class, and (3) the SplDoublyLinkedList class, which are mishandled during unserialization.
How severe is CVE-2015-6834?: CVE-2015-6834 has a CVSS 3.x base score of 9.8, 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 high.
Is CVE-2015-6834 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 47% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2015-6834?: CVE-2015-6834 primarily affects Php. In total, 43 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2015-6834?: 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-2015-6834 published?: CVE-2015-6834 was published on 2016-05-16 and last updated on 2026-06-17.

References

Affected products (43)

cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.0:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.1:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.2:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.3:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.4:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.5:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.6:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.7:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.8:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.9:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.10:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.11:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.12:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.13:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.14:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.15:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.16:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.17:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.18:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.19:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.20:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.21:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.22:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.23:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.24:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.25:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.26:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.27:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.5.28:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.0:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.1:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.2:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.3:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.4:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.5:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.6:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.7:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.8:*:*:*:*:*:*:*
cpe:2.3:a:php:php:5.6.9:*:*:*:*:*:*:*

More vulnerabilities in Php

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CVE-2011-3268 — Critical (CVSS 10.0): Buffer overflow in the crypt function in PHP before 5.3.7 allows context-dependent attackers to have an unspecified…
CVE-2009-4143 — Critical (CVSS 10.0): PHP before 5.2.12 does not properly handle session data, which has unspecified impact and attack vectors related to (1)…
CVE-2008-5557 — Critical (CVSS 10.0): Heap-based buffer overflow in ext/mbstring/libmbfl/filters/mbfilter_htmlent.c in the mbstring extension in PHP 4.3.0…

All CVEs affecting Php →

Threat intelligence

Threat-intel indicators referencing this CVE:

45.84.120.3 (ipv4-addr)
221.161.235.168 (ipv4-addr)
200.196.50.91 (ipv4-addr)
187.141.71.166 (ipv4-addr)
187.110.238.50 (ipv4-addr)
116.255.252.44 (ipv4-addr)
113.164.66.10 (ipv4-addr)
103.38.219.22 (ipv4-addr)