No exploitation reportedFix available

CVE-2015-8866

Q: Is CVE-2015-8866 actively exploited?

Active exploitation of CVE-2015-8866 has not been confirmed. Its EPSS score was 4.2% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2015-8866?

CVE-2015-8866 has a CVSS v3 base score of 9.6 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2016-05-22
Fixed in7.2.1 · 7.1.13 · 7.0.27 · 5.6.6 · 5.5.22
WeaknessCWE-611

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC

2016-05-2201:59CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2015-8866?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2015-8866?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

PHP

Branch	Affected	Fixed in	Source
7.2	≥ 7.2.0, < 7.2.1	7.2.1	NVD
7.1	≥ 7.1.0, < 7.1.13	7.1.13	NVD
7.0	≥ 7.0.0, < 7.0.27	7.0.27	NVD
5.6	≥ 5.6.0, < 5.6.6	5.6.6	NVD
5.5	≥ 5.5.0, < 5.5.22	5.5.22	NVD

Canonical ubuntu linux

Branch	Affected	Fixed in	Source
12.4	= 12.04	no fix published	NVD
14.4	= 14.04	no fix published	NVD
15.10	= 15.10	no fix published	NVD

Opensuse

Branch	Affected	Fixed in	Source
13.2	= 13.2	no fix published	NVD

3 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update PHP to 7.2.1 · 7.1.13 · 7.0.27 · 5.6.6 · 5.5.22

Advisories and patches

www.openwall.comPatch
www.php.netRelease Notes · Vendor Advisory
bugs.launchpad.netPatch
bugs.php.netPatch · Vendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.19.6read 2026-10-23
NVDCVSS 2.06.8read 2026-10-23
NVDweakness (CWE)CWE-611read 2026-10-23
FIRST EPSSEPSS score4.2 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Published: 2016-05-22
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2015-8866?

Is CVE-2015-8866 actively exploited?

Active exploitation of CVE-2015-8866 has not been confirmed. Its EPSS score was 4.2% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2015-8866?

CVE-2015-8866 has a CVSS v3 base score of 9.6 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.

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