CVE-2016-10033

CRITICALNVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score elevated to 9.8 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2025-07-07), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 9.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, nvd
Trending — 3 sources updated this weekExploited in the wild
9.8
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • 128 internet-exposed hosts are running an affected version right now
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS: 100%CVSS: 9.8Exploit: NoneExposed: 128

A fix is available — apply it.

The mailSend function in the isMail transport in PHPMailer before 5.2.18 might allow remote attackers to pass extra parameters to the mail command and consequently execute arbitrary code via a \" (backslash double quote) in a crafted Sender property.

Live · internet exposure

128 internet-exposed hosts are running an affected version of CVE-2016-10033 right now.

across 24 countries (United States, Germany, Singapore, United Kingdom, Netherlands)top: wordpress
See the live KEV-Exposure radar →Found passively from public internet-scan data — aggregate, host-redacted.

EchelonGraph is the only CVE feed that fuses live vulnerability intelligence with its own live internet-exposure radar — so you see not just that a CVE is exploited, but how much of the internet is exposed to it right now.

CVSS v3
9.8
EG Score
9.8(high)
EG Risk
99(Act)
EG Risk 99/100SSVC: Act

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation100% × 40%
Automatability100% × 15%
Action: Fix now — active exploitation, automatable, high impact.
EPSS
100.0%
KEV
⚠ Exploited

Published

December 30, 2016

Last Modified

April 21, 2026

Advisory Details (9)

Auto-updated Apr 30, 2026
No patch confirmed yet.
generic

About the CVE 2016 10033 and CVE 2016 10045 vulnerabilities · PHPMailer/PHPMailer Wiki · GitHub

https://github.com/PHPMailer/PHPMailer/wiki/About-the-CVE-2016-10033-and-CVE-2016-10045-vulnerabilities
generic

Release PHPMailer 5.2.18 · PHPMailer/PHPMailer · GitHub

https://github.com/PHPMailer/PHPMailer/releases/tag/v5.2.18
generic

[20161205] - PHPMailer Security Advisory

https://developer.joomla.org/security-centre/668-20161205-phpmailer-security-advisory.html
generic
http://www.securityfocus.com/bid/95108
generic
http://www.securityfocus.com/archive/1/539963/100/0/threaded
generic

Rapid7 Vulnerability Database

http://www.rapid7.com/db/modules/exploit/multi/http/phpmailer_arg_injection
generic

Full Disclosure: PHPMailer < 5.2.18 Remote Code Execution [CVE-2016-10033]

http://seclists.org/fulldisclosure/2016/Dec/78
generic

Packet Storm

http://packetstormsecurity.com/files/140350/PHPMailer-Sendmail-Argument-Injection.html
generic

Packet Storm

http://packetstormsecurity.com/files/140291/PHPMailer-Remote-Code-Execution.html

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibphp-phpmailer (5.2.14+dfsg-1ubuntu0.1~esm1) @ xenial2026-07-22ubuntu

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.

Affected Packages

(1 across 1 ecosystem)
Packagist(1)
PackageVulnerable rangeFixed inDependents
phpmailer/phpmailerv5.2.10 ... v5.2.9 (15 versions)5.2.18—

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 21× in last 7d / 152× 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 328 total refreshes for this CVE.

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

Publicly available exploits

(10 references)

Working exploit code is in the public domain (1 Metasploit module) (3 GitHub PoCs) (6 Exploit-DB entries). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoC0x00-0x00/CVE-2016-10033
    First seen Feb 9, 2018

    PHPMailer < 5.2.18 Remote Code Execution Exploit

    Open source ↗
  • GitHub PoCpedro823/cve-2016-10033-45
    First seen Nov 19, 2017

    Exploits CVE-2016-10033 and CVE-2016-10045

    Open source ↗
  • Exploit-DBEDB-42221
    First seen Jun 21, 2017

    PHPMailer < 5.2.20 with Exim MTA - Remote Code Execution

    Open source ↗
  • Exploit-DBEDB-42024✓ verified
    First seen May 17, 2017

    WordPress Plugin PHPMailer 4.6 - Host Header Command Injection (Metasploit)

    Open source ↗
  • Exploit-DBEDB-41996
    First seen May 11, 2017

    Vanilla Forums < 2.3 - Remote Code Execution

    Open source ↗
  • GitHub PoCGeneralTesler/CVE-2016-10033
    First seen May 10, 2017

    RCE against WordPress 4.6; Python port of https://exploitbox.io/vuln/WordPress-Exploit-4-6-RCE-CODE-EXEC-CVE-2016-10033.html

    Open source ↗
  • Exploit-DBEDB-41962
    First seen May 3, 2017

    WordPress Core 4.6 - Remote Code Execution

    Open source ↗
  • Metasploitexploit/unix/webapp/wp_phpmailer_host_header✓ verified
    First seen May 3, 2017

    WordPress PHPMailer Host Header Command Injection

    Open source ↗
  • Exploit-DBEDB-40986
    First seen Jan 2, 2017

    PHPMailer < 5.2.20 / SwiftMailer < 5.4.5-DEV / Zend Framework / zend-mail < 2.4.11 - 'AIO' 'PwnScriptum' Remote Code Execution

    Open source ↗
  • Exploit-DBEDB-40974
    First seen Dec 29, 2016

    PHPMailer < 5.2.18 - Remote Code Execution

    Open source ↗

Frequently asked(6)

What is CVE-2016-10033?
CVE-2016-10033 is a critical vulnerability published on December 30, 2016. The mailSend function in the isMail transport in PHPMailer before 5.2.18 might allow remote attackers to pass extra parameters to the mail command and consequently execute arbitrary code via a \" (backslash double quote) in a crafted Sender property.
When was CVE-2016-10033 disclosed?
CVE-2016-10033 was first published in the National Vulnerability Database on December 30, 2016, with the most recent update on April 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-10033 actively exploited?
Yes. CISA added CVE-2016-10033 to the Known Exploited Vulnerabilities catalog on July 7, 2025, affecting PHP PHPMailer. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.
What is the CVSS score of CVE-2016-10033?
CVE-2016-10033 has a CVSS v3 base score of 9.8 (NVD).
Which products are affected by CVE-2016-10033?
CVE-2016-10033 affects PHP PHPMailer. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.
How do I remediate CVE-2016-10033?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-10033, 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.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2016-10033

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