CRITICAL KEV
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
Published Dec 30, 2016 ·Due Jul 28, 2025
9.8
CRITICALCVSS 3.1
EPSS 99.71%
Description
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.
Affected products
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
9.8 CRITICAL NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality Impact High
Integrity Impact High
Availability Impact High
1 other source (GHSA) ▾
9.8 CRITICAL GHSA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality Impact High
Integrity Impact High
Availability Impact High
Exploit Maturity H
No CVSS v3.0 score for this CVE.
7.5 HIGH NVD
AV:N/AC:L/Au:N/C:P/I:P/A:P
Access Vector Network
Access Complexity Low
Authentication None
Confidentiality Impact Partial
Integrity Impact Partial
Availability Impact Partial
Listed in CISA KEV KEV
Date Added
Jul 7, 2025
Patch Due
Jul 28, 2025
Required Action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
ActiveAutomatable
YesTechnical Impact
TotalDecision
n/aAssessed Jul 17, 2025 · SSVC 2.0.3
99.71% 0.99714
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
EPSS probability 0.99714
Score over time
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (9 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 99.71% (0.99714) | 99.95th | v5 (v2026.06.15) |
| Jun 15, 2026 | 99.71% (0.99714) | 99.95th | v5 (v2026.06.15) |
| Mar 17, 2025 | 94.44% (0.94436) | 99.98th | v4 (v2025.03.14) |
| Dec 12, 2024 | 97.09% (0.97090) | 99.83th | v3 (v2023.03.01) |
| Jul 14, 2024 | 97.09% (0.97090) | 99.80th | v3 (v2023.03.01) |
| Feb 15, 2024 | 97.13% (0.97129) | 99.76th | v3 (v2023.03.01) |
| Mar 7, 2023 | 97.46% (0.97459) | 99.91th | v3 (v2023.03.01) |
| Mar 6, 2023 | 96.29% (0.96287) | 99.99th | v2 (v2022.01.01) |
| Feb 4, 2022 | 96.29% (0.96287) | 100.00th | v2 (v2022.01.01) |
References (26)
- http://packetstormsecurity.com/files/140291/PHPMailer-Remote-Code-Execution.html x_refsource_MISCExploitThird Party AdvisoryVDB Entry
- http://packetstormsecurity.com/files/140350/PHPMailer-Sendmail-Argument-Injection.html x_refsource_MISCExploitThird Party AdvisoryVDB Entry
- http://seclists.org/fulldisclosure/2016/Dec/78 mailing-listx_refsource_FULLDISCMailing ListPatchThird Party Advisory
- http://www.rapid7.com/db/modules/exploit/multi/http/phpmailer_arg_injection x_refsource_MISCExploitThird Party Advisory
- http://www.securityfocus.com/archive/1/539963/100/0/threaded mailing-listx_refsource_BUGTRAQBroken LinkThird Party AdvisoryVDB Entry
- http://www.securityfocus.com/bid/95108 vdb-entryx_refsource_BIDBroken LinkExploitThird Party AdvisoryVDB Entry
- http://www.securitytracker.com/id/1037533 vdb-entryx_refsource_SECTRACKBroken LinkThird Party AdvisoryVDB Entry
- https://developer.joomla.org/security-centre/668-20161205-phpmailer-security-advisory.html x_refsource_CONFIRMThird Party Advisory
- https://github.com/FriendsOfPHP/security-advisories/blob/master/phpmailer/phpmailer/CVE-2016-10033.yaml
- https://github.com/PHPMailer/PHPMailer/releases/tag/v5.2.18 x_refsource_CONFIRMPatchVendor Advisory
- https://github.com/PHPMailer/PHPMailer/security/advisories/GHSA-5f37-gxvh-23v6
- https://github.com/PHPMailer/PHPMailer/wiki/About-the-CVE-2016-10033-and-CVE-2016-10045-vulnerabilities x_refsource_CONFIRMPatchVendor Advisory
- https://github.com/advisories/GHSA-5f37-gxvh-23v6 Advisory
- https://legalhackers.com/advisories/PHPMailer-Exploit-Remote-Code-Exec-CVE-2016-10033-Vuln.html x_refsource_MISCExploitPatchThird Party Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2016-10033
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2016-10033 government-resourceUS Government Resource
- https://www.drupal.org/psa-2016-004 x_refsource_CONFIRMThird Party Advisory
- https://www.exploit-db.com/exploits/40968 exploitx_refsource_EXPLOIT-DBPatchThird Party AdvisoryVDB Entry
- https://www.exploit-db.com/exploits/40969 exploitx_refsource_EXPLOIT-DBThird Party AdvisoryVDB Entry
- https://www.exploit-db.com/exploits/40970 exploitx_refsource_EXPLOIT-DBPatchThird Party AdvisoryVDB Entry
- https://www.exploit-db.com/exploits/40974 exploitx_refsource_EXPLOIT-DBThird Party AdvisoryVDB Entry
- https://www.exploit-db.com/exploits/40986 exploitx_refsource_EXPLOIT-DBThird Party AdvisoryVDB Entry
- https://www.exploit-db.com/exploits/41962 exploitx_refsource_EXPLOIT-DBThird Party AdvisoryVDB Entry
- https://www.exploit-db.com/exploits/41996 exploitx_refsource_EXPLOIT-DBThird Party AdvisoryVDB Entry
- https://www.exploit-db.com/exploits/42024 exploitx_refsource_EXPLOIT-DBThird Party AdvisoryVDB Entry
- https://www.exploit-db.com/exploits/42221 exploitx_refsource_EXPLOIT-DBThird Party AdvisoryVDB Entry
Change history (0)
No recorded changes yet.
Sources
CVE.org / MITRE
Status PUBLISHED
Assigner mitre
Published Dec 30, 2016
Updated Oct 21, 2025
Reserved Dec 22, 2016
Link CVE-2016-10033
CISA Vulnrichment
GHSA-5F37-GXVH-23V6 Updated Jul 17, 2025