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CVE-2015-6838

27
FAUCET Score

CVE-2015-6838 is a NULL pointer dereference vulnerability in PHP versions prior to 5.4.45, 5.5.29, and 5.6.13, specifically within the xsl_ext_function_php function when used with libxml2 versions older than 2.9.2. This flaw allows remote attackers to trigger a denial of service by providing a specially crafted XML document. The vulnerability carries a CVSS v3 score of 7.5 (High), indicating a critical severity. It is easily exploitable over the network with low attack complexity, requiring no user interaction or privileges, and its primary impact is application availability. There is no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage regarding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
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:*:*:*:*:*:*
5.6.0CPE matchmatch criteria
cpe:2.3:a:php:php:5.6.0:alpha5:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
7.28%
Probability of exploitation in next 30 days
EPSS Percentile
93.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0728 is in the 89th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (12)

redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6Fixed in: rh-php56-php-0:5.6.5-8.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6.6 EUSFixed in: rh-php56-php-0:5.6.5-8.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUSFixed in: rh-php56-php-0:5.6.5-8.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: rh-php56-php-0:5.6.5-8.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.1 EUSFixed in: rh-php56-php-0:5.6.5-8.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.2 EUSFixed in: rh-php56-php-0:5.6.5-8.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-2015-6838Low

php: NULL pointer dereference in XSLTProcessor class

Jun 9, 2015

References

php.net / ChangeLog-5.php
bugs.php.net / bug.php
security.gentoo.org / glsa/201606-10
debian.org / security/2015/dsa-3358
securityfocus.com / bid/76733
securitytracker.com / id/1033548