CVE-2016-4538

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-14. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 6%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

The bcpowmod function in ext/bcmath/bcmath.c in PHP before 5.5.35, 5.6.x before 5.6.21, and 7.x before 7.0.6 modifies certain data structures without considering whether they are copies of the _zero_, _one_, or _two_ global variable, which allows remote attackers to cause a denial of service or possibly have unspecified other impact via a crafted call.

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
92.7%
KEV
Not listed

Published

May 22, 2016

Last Modified

May 6, 2026

Advisory Details (7)

Auto-updated May 8, 2026
No patch confirmed yet.
generic

PHP :: Sec Bug #72093 :: bcpowmod accepts negative scale and corrupts _one_ definition

https://bugs.php.net/bug.php?id=72093
generic
http://www.securityfocus.com/bid/90173
generic

oss-security - CVE Request: PHP: several issues fixed with 7.0.6, 5.6.21 and 5.5.35

http://www.openwall.com/lists/oss-security/2016/05/05/21
generic

[SECURITY] [DSA 3602-1] php5 security update

http://www.debian.org/security/2016/dsa-3602
generic
http://rhn.redhat.com/errata/RHSA-2016-2750.html
generic

PHP: PHP 7 ChangeLog

http://php.net/ChangeLog-7.php
generic

PHP: PHP 5 ChangeLog

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

Vendor Advisories for CVE-2016-4538(1)

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

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuphp7.0-zip (7.0.4-7ubuntu2.1) @ xenial2026-05-20ubuntu
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.

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 9× in last 7d / 42× 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.

Showing the most recent 100 of 102 total refreshes for this CVE.

  1. 2026-07-07 13:42 UTCEPSS rescore
  2. 2026-07-06 16:24 UTCEPSS rescore
  3. 2026-07-06 16:24 UTCEPSS rescore
  4. 2026-07-06 02:20 UTCEPSS rescore
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  6. 2026-07-05 02:27 UTCEPSS rescore
  7. 2026-07-04 06:28 UTCEPSS rescore
  8. 2026-07-01 15:02 UTCEPSS rescore
  9. 2026-06-30 23:19 UTCEPSS rescore
  10. 2026-06-29 14:03 UTCEPSS rescore
  11. 2026-06-28 14:04 UTCEPSS rescore
  12. 2026-06-28 04:53 UTCEPSS rescore
  13. 2026-06-27 03:05 UTCEPSS rescore
  14. 2026-06-27 03:05 UTCEPSS rescore
  15. 2026-06-25 13:47 UTCEPSS rescore
  16. 2026-06-25 13:47 UTCEPSS rescore
  17. 2026-06-24 14:02 UTCEPSS rescore
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  19. 2026-06-23 21:30 UTCEPSS rescore
  20. 2026-06-22 14:23 UTCEPSS rescore
  21. 2026-06-21 14:54 UTCEPSS rescore
  22. 2026-06-21 14:54 UTCEPSS rescore
  23. 2026-06-21 01:57 UTCEPSS rescore
  24. 2026-06-21 01:57 UTCEPSS rescore
  25. 2026-06-19 19:23 UTCEPSS rescore
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  1. 2026-06-19 19:23 UTCEPSS rescore
  2. 2026-06-19 11:25 UTCOSV refresh
  3. 2026-06-18 17:50 UTCEPSS rescore
  4. 2026-06-17 17:50 UTCEPSS rescore
  5. 2026-06-17 17:50 UTCEPSS rescore
  6. 2026-06-16 17:50 UTCEPSS rescore
  7. 2026-06-16 17:50 UTCEPSS rescore
  8. 2026-06-15 17:45 UTCEPSS rescore
  9. 2026-06-14 23:14 UTCEPSS rescore
  10. 2026-06-13 22:57 UTCEPSS rescore
  11. 2026-06-13 22:57 UTCEPSS rescore
  12. 2026-06-12 23:09 UTCEPSS rescore
  13. 2026-06-12 23:09 UTCEPSS rescore
  14. 2026-06-11 13:57 UTCEPSS rescore
  15. 2026-06-10 22:15 UTCEPSS rescore
  16. 2026-06-10 13:18 UTCEPSS rescore
  17. 2026-06-08 14:14 UTCEPSS rescore
  18. 2026-06-07 15:22 UTCEPSS rescore
  19. 2026-06-07 15:22 UTCEPSS rescore
  20. 2026-06-06 13:45 UTCEPSS rescore
  21. 2026-06-05 22:44 UTCEPSS rescore
  22. 2026-06-05 06:08 UTCEPSS rescore
  23. 2026-06-05 06:08 UTCEPSS rescore
  24. 2026-06-04 13:10 UTCEPSS rescore
  25. 2026-06-04 13:10 UTCEPSS rescore
  26. 2026-06-02 20:10 UTCEPSS rescore
  27. 2026-06-01 13:49 UTCEPSS rescore
  28. 2026-06-01 13:49 UTCEPSS rescore
  29. 2026-05-31 22:28 UTCEPSS rescore
  30. 2026-05-31 22:28 UTCEPSS rescore
  31. 2026-05-31 00:14 UTCEPSS rescore
  32. 2026-05-30 19:53 UTCOSV refresh
  33. 2026-05-29 13:41 UTCEPSS rescore
  34. 2026-05-28 13:42 UTCEPSS rescore
  35. 2026-05-28 13:42 UTCEPSS rescore
  36. 2026-05-27 13:38 UTCEPSS rescore
  37. 2026-05-27 13:38 UTCEPSS rescore
  38. 2026-05-26 13:42 UTCEPSS rescore
  39. 2026-05-24 16:43 UTCEPSS rescore
  40. 2026-05-22 21:15 UTCEPSS rescore
  41. 2026-05-22 21:15 UTCEPSS rescore
  42. 2026-05-21 22:40 UTCEPSS rescore
  43. 2026-05-20 22:37 UTCEPSS rescore
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  45. 2026-05-20 22:37 UTCEPSS rescore
  46. 2026-05-20 11:21 UTCEPSS rescore
  47. 2026-05-20 11:21 UTCEPSS rescore
  48. 2026-05-20 11:21 UTCEPSS rescore
  49. 2026-05-20 08:07 UTCEG score recompute
  50. 2026-05-20 08:07 UTCVendor advisory
  51. 2026-05-20 08:07 UTCGHSA enrichment
  52. 2026-05-20 04:14 UTCEG score recompute
  53. 2026-05-20 04:14 UTCVendor advisory
  54. 2026-05-20 04:14 UTCGHSA enrichment
  55. 2026-05-20 00:22 UTCEG score recompute
  56. 2026-05-20 00:22 UTCVendor advisory
  57. 2026-05-20 00:22 UTCGHSA enrichment
  58. 2026-05-19 20:30 UTCEG score recompute
  59. 2026-05-19 20:30 UTCVendor advisory
  60. 2026-05-19 20:30 UTCGHSA enrichment
  61. 2026-05-19 16:36 UTCEG score recompute
  62. 2026-05-19 16:36 UTCVendor advisory
  63. 2026-05-19 16:36 UTCGHSA enrichment
  64. 2026-05-19 12:39 UTCEG score recompute
  65. 2026-05-19 12:39 UTCVendor advisory
  66. 2026-05-19 12:39 UTCGHSA enrichment
  67. 2026-05-19 08:35 UTCEG score recompute
  68. 2026-05-19 08:35 UTCVendor advisory
  69. 2026-05-19 08:34 UTCGHSA enrichment
  70. 2026-05-19 04:41 UTCEG score recompute
  71. 2026-05-19 04:41 UTCVendor advisory
  72. 2026-05-19 04:41 UTCGHSA enrichment
  73. 2026-05-19 00:48 UTCEG score recompute
  74. 2026-05-19 00:48 UTCVendor advisory
  75. 2026-05-19 00:48 UTCGHSA enrichment

Related CVEs(same vendor)

Frequently asked(5)

What is CVE-2016-4538?
CVE-2016-4538 is a critical vulnerability published on May 22, 2016. The bcpowmod function in ext/bcmath/bcmath.c in PHP before 5.5.35, 5.6.x before 5.6.21, and 7.x before 7.0.6 modifies certain data structures without considering whether they are copies of the zero, one, or two global variable, which allows remote attackers to cause a denial of service or possibly…
When was CVE-2016-4538 disclosed?
CVE-2016-4538 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-2016-4538 actively exploited?
CVE-2016-4538 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 92.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2016-4538?
CVE-2016-4538 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2016-4538?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-4538, 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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