Is CVE-2015-8866 in the CISA KEV catalog?

No. CVE-2015-8866 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2015-8866?

CVE-2015-8866 has a CVSS v3 base score of 9.6 (CRITICAL).

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

CVE-2015-8866 has an EPSS score of 4.03% (89th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2015-8866

CRITICALEPSS 89th pctl

9.6

CVSS v3

NVD

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.

CWE-611XML External Entity (XXE)

How to fix

Remediation Available

phpNVD

Affected:>= 7.2.0, < 7.2.1Fixed in:7.2.1CVE-2015-8866derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

4.03%probability of exploitation in 30 days

89thpercentile

Elevated risk: more likely to be exploited than 89% of all known CVEs.

References

Patch3

Vendor Advisory1

php.net

Third-Party Advisory7

Other references1

git.php.net

Related Vulnerabilities

Other CWE-611 (XML External Entity (XXE)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-34102	Critical	9.8	100%	KEV	Fix
CVE-2019-9670	Critical	9.8	100%	KEV	Fix
CVE-2022-28219	Critical	9.8	97%	-	-
CVE-2024-22024	High	8.3	95%	-	-
CVE-2024-38653	High	7.5	92%	-	-
CVE-2017-12629	Critical	9.8	92%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-06.