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CVE-2015-8866

25
FAUCET Score

CVE-2015-8866 describes a critical vulnerability in PHP versions before 5.5.22 and 5.6.6, specifically when PHP-FPM is utilized. This flaw, located in ext/libxml/libxml.c, allows attackers to conduct XML External Entity (XXE) and XML Entity Expansion (XEE) attacks by exploiting a lack of thread isolation for libxml_disable_entity_loader changes. Affected products include canonical, opensuse, php, and suse. With a CVSS score of 9.6 (CRITICAL), this vulnerability is easily exploitable over the network with low attack complexity, requiring user interaction. Successful exploitation can lead to complete compromise of confidentiality, integrity, and availability. The associated CWE is CWE-611. Despite its high severity, there is no evidence of active exploitation, and it is not listed in the CISA KEV catalog. There are no known public exploits (Metasploit, Nuclei, ExploitDB), and it has received minimal community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
>= 5.5.0, < 5.5.22CPE matchmatch criteria
cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
>= 5.6.0, < 5.6.6CPE matchmatch criteria
cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
>= 7.0.0, < 7.0.27CPE matchmatch criteria
cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
>= 7.1.0, < 7.1.13CPE matchmatch criteria
cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
>= 7.2.0, < 7.2.1CPE matchmatch criteria
cpe:2.3:a:php:php:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.6CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
6.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
4.03%
Probability of exploitation in next 30 days
EPSS Percentile
89.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0403 is in the 93rd percentile among its peer group of 834 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, 0.8 Bluesky, 0.5 Mastodon, and 1.2 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 0.1 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-2015-8866Low

php: libxml_disable_entity_loader setting is shared between threads

Apr 21, 2016

References

git.php.net
lists.opensuse.org / opensuse-security-announce/2016-05/msg00031.html
Mailing ListThird Party Advisory
lists.opensuse.org / opensuse-security-announce/2016-05/msg00033.html
Mailing ListThird Party Advisory
lists.opensuse.org / opensuse-security-announce/2016-05/msg00056.html
Mailing ListThird Party Advisory
rhn.redhat.com / errata/RHSA-2016-2750.html
Third Party Advisory
bugs.launchpad.net / ubuntu/+source/php5/+bug/1509817
Issue TrackingPatchThird Party Advisory
bugs.php.net / bug.php
ExploitIssue TrackingPatchVendor Advisory
openwall.com / lists/oss-security/2016/04/24/1
Mailing ListPatchThird Party Advisory
php.net / ChangeLog-5.php
Release NotesVendor Advisory
securityfocus.com / bid/87470
Third Party AdvisoryVDB Entry
ubuntu.com / usn/USN-2952-1
Third Party Advisory
ubuntu.com / usn/USN-2952-2
Third Party Advisory