CVE-2016-6296

What it is

Integer signedness error in the simplestring_addn function in simplestring.c in xmlrpc-epi through 0.54.2, as used in PHP before 5.5.38, 5.6.x before 5.6.24, and 7.x before 7.0.9, allows remote attackers to cause a denial of service (heap-based buffer overflow) or possibly have unspecified other impact via a long first argument to the PHP xmlrpc_encode_request function.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering, service disruption.

Exploit odds

6.3% chance of exploitation in the next 30 days (EPSS).

Fix

No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

1. 2016-07-24 00:00 UTC ReservedThe CVE id was reserved by its CNA
2. 2016-07-25 14:59 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-06-17 00:50 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 6.3% in the next 30 days (EPSS).
• Severity: 9.8 CRITICAL (CVSS).
• Fix: none linked yet, which raises it.

Details

Published

2016-07-25 14:59 UTC

Last modified

2026-06-17 00:50 UTC

Exploit probability

6.3% · EPSS, next 30 days

Weakness

CWE-119 · Buffer errors

Record status

Modified

Affected

• PHP ≤ 5.5.37
• PHP 5.6.0
• PHP 5.6.1
• PHP 5.6.2
• PHP 5.6.3
• PHP 5.6.4
• PHP 5.6.5
• PHP 5.6.6

Attack profile CVSS 3.0 · 9.8

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Is it in your code?

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