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CVE-2016-6296

26
FAUCET Score

CVE-2016-6296 is an integer signedness error in the simplestring_addn function within xmlrpc-epi, affecting PHP versions before 5.5.38, 5.6.24, and 7.0.9. This flaw allows remote attackers to trigger a heap-based buffer overflow, leading to a denial of service or potentially other unspecified impacts, by providing a long argument to the xmlrpc_encode_request function. With a CVSS score of 9.8 (Critical), this vulnerability is easily exploitable over the network with low attack complexity and no user interaction, posing a high risk to confidentiality, integrity, and availability. Despite its critical severity, there is no evidence of active exploitation, no known public exploit code (Metasploit, Nuclei, ExploitDB), and minimal community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
<= 5.5.37CPE matchmatch criteria
cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
5.6.0CPE matchmatch criteria
cpe:2.3:a:php:php:5.6.0:alpha1:*:*:*:*:*:*
5.6.0CPE matchmatch criteria
cpe:2.3:a:php:php:5.6.0:alpha2:*:*:*:*:*:*
5.6.0CPE matchmatch criteria
cpe:2.3:a:php:php:5.6.0:alpha3:*:*:*:*:*:*
5.6.0CPE matchmatch criteria
cpe:2.3:a:php:php:5.6.0:alpha4:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

9.8CRITICAL

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
6.27%
Probability of exploitation in next 30 days
EPSS Percentile
92.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0627 is in the 87th percentile among its peer group of 36,835 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (21)

redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6Fixed in: rh-php56-0:2.3-1.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6Fixed in: rh-php56-php-0:5.6.25-1.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6Fixed in: rh-php56-php-pear-1:1.9.5-4.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUSFixed in: rh-php56-0:2.3-1.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUSFixed in: rh-php56-php-0:5.6.25-1.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUSFixed in: rh-php56-php-pear-1:1.9.5-4.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-php56-0:2.3-1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-php56-php-0:5.6.25-1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-php56-php-pear-1:1.9.5-4.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.2 EUSFixed in: rh-php56-0:2.3-1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.2 EUSFixed in: rh-php56-php-0:5.6.25-1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.2 EUSFixed in: rh-php56-php-pear-1:1.9.5-4.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.3 EUSFixed in: rh-php56-0:2.3-1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.3 EUSFixed in: rh-php56-php-0:5.6.25-1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.3 EUSFixed in: rh-php56-php-pear-1:1.9.5-4.el7
View patch
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: php
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: php53
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: php
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: php
redhatend of lifevia redhat_api
Product: Red Hat Software CollectionsFixed in: php54-php
redhatend of lifevia redhat_api
Product: Red Hat Software CollectionsFixed in: php55-php

Vendor Advisories (1)

redhatCVE-2016-6296Moderate

php: Heap buffer overflow vulnerability in simplestring_addn in simplestring.c

Jul 17, 2016

References

git.php.net
lists.apple.com / archives/security-announce/2016/Sep/msg00006.html
openwall.com / lists/oss-security/2016/07/24/2
Mailing List
php.net / ChangeLog-5.php
Release Notes
php.net / ChangeLog-7.php
Release Notes
rhn.redhat.com / errata/RHSA-2016-2750.html
bugs.php.net / 72606
ExploitIssue Tracking
lists.debian.org / debian-lts-announce/2019/11/msg00029.html
security.gentoo.org / glsa/201611-22
support.apple.com / HT207170
debian.org / security/2016/dsa-3631
securityfocus.com / bid/92095
Third Party AdvisoryVDB Entry
securitytracker.com / id/1036430
ubuntu.com / usn/USN-3059-1