CVE-2015-8866

CRITICALNVD 9.69.6—
EchelonGraph scoreMEDIUM confidence

Score 9.6 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-14. NVD baseline CVSS 9.6; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.6
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 4%CVSS: 9.6Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
9.6
EG Score
9.6(medium)
EPSS
89.4%
KEV
Not listed

Published

May 22, 2016

Last Modified

May 6, 2026

Advisory Details (4)

Auto-updated May 9, 2026
No patch confirmed yet.
generic
http://www.securityfocus.com/bid/87470
generic

PHP: PHP 5 ChangeLog

http://www.php.net/ChangeLog-5.php
generic

oss-security - Re: CVE request: PHP issues fixed in 7.0.5, 5.6.20 and 5.5.34 releases

http://www.openwall.com/lists/oss-security/2016/04/24/1
generic
http://rhn.redhat.com/errata/RHSA-2016-2750.html

Vendor Advisories for CVE-2015-8866(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatrh-php56-php-pear-1:1.9.5-4.el72016-11-15redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Data Freshness Timeline

(refreshed 7× in last 7d / 35× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-06 16:24 UTCEPSS rescore
  2. 2026-07-06 02:20 UTCEPSS rescore
  3. 2026-07-05 02:26 UTCEPSS rescore
  4. 2026-07-04 06:28 UTCEPSS rescore
  5. 2026-07-01 15:02 UTCEPSS rescore
  6. 2026-06-30 23:19 UTCEPSS rescore
  7. 2026-06-30 23:19 UTCEPSS rescore
  8. 2026-06-28 04:53 UTCEPSS rescore
  9. 2026-06-27 03:05 UTCEPSS rescore
  10. 2026-06-25 13:47 UTCEPSS rescore
  11. 2026-06-25 13:47 UTCEPSS rescore
  12. 2026-06-24 14:02 UTCEPSS rescore
  13. 2026-06-24 14:02 UTCEPSS rescore
  14. 2026-06-23 21:30 UTCEPSS rescore
  15. 2026-06-21 14:54 UTCEPSS rescore
  16. 2026-06-21 14:54 UTCEPSS rescore
  17. 2026-06-21 01:57 UTCEPSS rescore
  18. 2026-06-21 01:57 UTCEPSS rescore
  19. 2026-06-19 19:23 UTCEPSS rescore
  20. 2026-06-19 19:23 UTCEPSS rescore
  21. 2026-06-18 17:50 UTCEPSS rescore
  22. 2026-06-17 17:50 UTCEPSS rescore
  23. 2026-06-17 17:49 UTCEPSS rescore
  24. 2026-06-16 17:50 UTCEPSS rescore
  25. 2026-06-16 17:50 UTCEPSS rescore
Show 41 more
  1. 2026-06-15 17:45 UTCEPSS rescore
  2. 2026-06-14 23:14 UTCEPSS rescore
  3. 2026-06-13 22:57 UTCEPSS rescore
  4. 2026-06-12 23:09 UTCEPSS rescore
  5. 2026-06-12 23:09 UTCEPSS rescore
  6. 2026-06-11 13:57 UTCEPSS rescore
  7. 2026-06-11 13:57 UTCEPSS rescore
  8. 2026-06-10 22:15 UTCEPSS rescore
  9. 2026-06-10 13:18 UTCEPSS rescore
  10. 2026-06-08 14:14 UTCEPSS rescore
  11. 2026-06-06 13:45 UTCEPSS rescore
  12. 2026-06-05 22:44 UTCEPSS rescore
  13. 2026-06-05 06:08 UTCEPSS rescore
  14. 2026-06-05 06:08 UTCEPSS rescore
  15. 2026-06-04 13:10 UTCEPSS rescore
  16. 2026-06-04 13:10 UTCEPSS rescore
  17. 2026-06-02 20:10 UTCEPSS rescore
  18. 2026-05-31 22:28 UTCEPSS rescore
  19. 2026-05-31 22:28 UTCEPSS rescore
  20. 2026-05-31 00:14 UTCEPSS rescore
  21. 2026-05-29 13:41 UTCEPSS rescore
  22. 2026-05-28 13:42 UTCEPSS rescore
  23. 2026-05-28 13:42 UTCEPSS rescore
  24. 2026-05-27 13:38 UTCEPSS rescore
  25. 2026-05-27 13:38 UTCEPSS rescore
  26. 2026-05-26 13:41 UTCEPSS rescore
  27. 2026-05-26 07:16 UTCEPSS rescore
  28. 2026-05-26 07:16 UTCEPSS rescore
  29. 2026-05-24 16:43 UTCEPSS rescore
  30. 2026-05-22 21:15 UTCEPSS rescore
  31. 2026-05-22 20:15 UTCEG score recompute
  32. 2026-05-22 20:15 UTCVendor advisory
  33. 2026-05-22 20:15 UTCGHSA enrichment
  34. 2026-05-21 22:40 UTCEPSS rescore
  35. 2026-05-20 22:37 UTCEPSS rescore
  36. 2026-05-20 22:37 UTCEPSS rescore
  37. 2026-05-20 11:21 UTCEPSS rescore
  38. 2026-05-20 11:21 UTCEPSS rescore
  39. 2026-05-20 11:21 UTCEPSS rescore
  40. 2026-05-18 21:30 UTCEPSS rescore
  41. 2026-05-18 21:30 UTCEPSS rescore

Related CVEs(same vendor)

Frequently asked(5)

What is CVE-2015-8866?
CVE-2015-8866 is a critical vulnerability published on May 22, 2016. 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 libxmldisableentity_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…
When was CVE-2015-8866 disclosed?
CVE-2015-8866 was first published in the National Vulnerability Database on May 22, 2016, with the most recent update on May 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2015-8866 actively exploited?
CVE-2015-8866 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 89.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2015-8866?
CVE-2015-8866 has a CVSS v3 base score of 9.6 (NVD).
How do I remediate CVE-2015-8866?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2015-8866, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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