CVE-2015-8866

Exp

ext/libxml/libxml.c in PHP before 5.5.22 and 5.6.x before 5.6.6, when PHP-FPM is used, does not isolate each thread from libxml_disable_entity_loader changes in other threads, which allows remote attackers to conduct XML External Entity (XXE) and XML Entity Expansion (XEE) attacks via a crafted XML document, a related issue to CVE-2015-5161.

Published: 2016-05-22 Last update: 2026-05-06 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2015-8866 is rated High Exploit Risk (84.4/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 3.53%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2015-8866

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2015-8866

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-01-21 3.05% 3.53% +0.48%
2 2025-12-28 1.98% 3.05% +1.07%
3 2025-12-27 — 1.98% —

Full EPSS history (19 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2015-8866

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.6 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 6.0 [email protected]
6.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 6.4 [email protected]

Weakness enumeration for CVE-2015-8866

OS Trackers for CVE-2015-8866

vendor priority summary link
redhat low — https://access.redhat.com/security/cve/CVE-2015-8866
suse medium CVE-2015-8866 severity moderate: SUSE including 408 source package names (apache2-mod_php5-5.2.14-0.7.30.79.1, apache2-mod_php5-5.5.14-56.1, …), 1027 product×package rows across 26 product lines (SUSE Enterprise Storage 7.1, SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS, … (26 product lines)): Known Not Affected 558, Fixed 469. https://www.suse.com/security/cve/CVE-2015-8866/
ubuntu medium CVE-2015-8866 medium priority: Ubuntu including 1 source packages (php5), 5 status rows across 5 suites (precise, trusty, upstream, wily, xenial): released 3, DNE 1, not-affected 1. https://ubuntu.com/security/CVE-2015-8866

Affected software / configurations for CVE-2015-8866

Vendor Product Version Raw CPE
php php >= 5.5.0, < 5.5.22 cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
php php >= 5.6.0, < 5.6.6 cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
php php >= 7.0.0, < 7.0.27 cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
php php >= 7.1.0, < 7.1.13 cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
php php >= 7.2.0, < 7.2.1 cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
canonical ubuntu_linux 12.04 cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:-:*:*:*
canonical ubuntu_linux 14.04 cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:*
canonical ubuntu_linux 15.10 cpe:2.3:o:canonical:ubuntu_linux:15.10:*:*:*:*:*:*:*
opensuse leap 42.1 cpe:2.3:o:opensuse:leap:42.1:*:*:*:*:*:*:*
opensuse opensuse 13.2 cpe:2.3:o:opensuse:opensuse:13.2:*:*:*:*:*:*:*
suse linux_enterprise_module_for_web_scripting 12 cpe:2.3:o:suse:linux_enterprise_module_for_web_scripting:12:*:*:*:*:*:*:*
suse linux_enterprise_software_development_kit 12 cpe:2.3:o:suse:linux_enterprise_software_development_kit:12:-:*:*:*:*:*:*
suse linux_enterprise_software_development_kit 12 cpe:2.3:o:suse:linux_enterprise_software_development_kit:12:sp1:*:*:*:*:*:*

References for CVE-2015-8866

URL Tags
http://git.php.net/?p=php-src.git%3Ba=commit%3Bh=de31324c221c1791b26350ba106cc26bad23ace9
http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00031.html Mailing List Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00033.html Mailing List Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00056.html Mailing List Third Party Advisory
http://rhn.redhat.com/errata/RHSA-2016-2750.html Third Party Advisory
http://www.openwall.com/lists/oss-security/2016/04/24/1 Mailing List Patch Third Party Advisory
http://www.php.net/ChangeLog-5.php Release Notes Vendor Advisory
http://www.securityfocus.com/bid/87470 Third Party Advisory VDB Entry
http://www.ubuntu.com/usn/USN-2952-1 Third Party Advisory
http://www.ubuntu.com/usn/USN-2952-2 Third Party Advisory
https://bugs.launchpad.net/ubuntu/+source/php5/+bug/1509817 Issue Tracking Patch Third Party Advisory
https://bugs.php.net/bug.php?id=64938 Exploit Issue Tracking Patch Vendor Advisory
cvelogic Threat Intelligence