CVE-2016-10033

Exp

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: 2016-12-30 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2016-10033 is rated Critical Active Threat (100/100): CVSS Critical severity, with high exploitation likelihood (EPSS 99.71%, 100th percentile). CISA KEV confirms active exploitation (added 2025-07-07) affecting PHP / PHPMailer. a weakness (CWE-88) Unauthenticated remote administrative access may be possible. EPSS rose +5.27% over the last day, indicating growing attacker interest. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2016-10033

Name: PHPMailer Command Injection Vulnerability · CISA KEV detail

Exploit added: 2025-07-07

Action due: 2025-07-28

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.

Public exploit references (Exploit-DB) for CVE-2016-10033

EDB-ID Source Kind Published Link
42221 exploit_db edb 2017-06-21 Exploit-DB ↗
42024 exploit_db edb 2017-05-17 Exploit-DB ↗
41996 exploit_db edb 2017-05-11 Exploit-DB ↗
41962 exploit_db edb 2017-05-03 Exploit-DB ↗
40986 exploit_db edb 2017-01-02 Exploit-DB ↗
40974 exploit_db edb 2016-12-29 Exploit-DB ↗
40969 exploit_db edb 2016-12-27 Exploit-DB ↗
40968 exploit_db edb 2016-12-26 Exploit-DB ↗
40970 exploit_db edb 2016-12-25 Exploit-DB ↗
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Exploit prediction scoring system (EPSS) score for CVE-2016-10033

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 94.44% 99.71% +5.27%
2 2026-05-27 94.47% 94.44% -0.02%
3 2026-05-09 — 94.47% —

Full EPSS history (29 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-10033

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2016-10033

GitHub Security Advisory for CVE-2016-10033

GHSA-5f37-gxvh-23v6 · Severity: critical · Ecosystem: composer — Remote code execution in PHPMailer

OS Trackers for CVE-2016-10033

vendor priority summary link
debian not yet assigned CVE-2016-10033 not yet assigned priority: Debian including 1 source packages (libphp-phpmailer), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2016-10033
ubuntu medium CVE-2016-10033 medium priority: Ubuntu including 1 source packages (libphp-phpmailer), 16 status rows across 16 suites (artful, bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, precise, trusty, upstream, xenial, yakkety, zesty): not-affected 11, ignored 2, released 2, DNE 1. https://ubuntu.com/security/CVE-2016-10033

Affected software / configurations for CVE-2016-10033

Vendor Product Version Raw CPE
phpmailer_project phpmailer < 5.2.18 cpe:2.3:a:phpmailer_project:phpmailer:*:*:*:*:*:*:*:*
wordpress wordpress <= 4.7 cpe:2.3:a:wordpress:wordpress:*:*:*:*:*:*:*:*
joomla joomla\! >= 1.5.0, <= 3.6.5 cpe:2.3:a:joomla:joomla\!:*:*:*:*:*:*:*:*

References for CVE-2016-10033

URL Tags
http://packetstormsecurity.com/files/140291/PHPMailer-Remote-Code-Execution.html Exploit Third Party Advisory VDB Entry
http://packetstormsecurity.com/files/140350/PHPMailer-Sendmail-Argument-Injection.html Exploit Third Party Advisory VDB Entry
http://seclists.org/fulldisclosure/2016/Dec/78 Mailing List Patch Third Party Advisory
http://www.rapid7.com/db/modules/exploit/multi/http/phpmailer_arg_injection Exploit Third Party Advisory
http://www.securityfocus.com/archive/1/539963/100/0/threaded Broken Link Third Party Advisory VDB Entry
http://www.securityfocus.com/bid/95108 Broken Link Exploit Third Party Advisory VDB Entry
http://www.securitytracker.com/id/1037533 Broken Link Third Party Advisory VDB Entry
https://developer.joomla.org/security-centre/668-20161205-phpmailer-security-advisory.html Third Party Advisory
https://github.com/PHPMailer/PHPMailer/releases/tag/v5.2.18 Patch Vendor Advisory
https://github.com/PHPMailer/PHPMailer/wiki/About-the-CVE-2016-10033-and-CVE-2016-10045-vulnerabilities Patch Vendor Advisory
https://legalhackers.com/advisories/PHPMailer-Exploit-Remote-Code-Exec-CVE-2016-10033-Vuln.html Exploit Patch Third Party Advisory
https://www.drupal.org/psa-2016-004 Third Party Advisory
https://www.exploit-db.com/exploits/40968/ Exploit Patch Third Party Advisory VDB Entry
https://www.exploit-db.com/exploits/40969/ Exploit Third Party Advisory VDB Entry
https://www.exploit-db.com/exploits/40970/ Exploit Patch Third Party Advisory VDB Entry
https://www.exploit-db.com/exploits/40974/ Exploit Third Party Advisory VDB Entry
https://www.exploit-db.com/exploits/40986/ Exploit Third Party Advisory VDB Entry
https://www.exploit-db.com/exploits/41962/ Exploit Third Party Advisory VDB Entry
https://www.exploit-db.com/exploits/41996/ Exploit Third Party Advisory VDB Entry
https://www.exploit-db.com/exploits/42024/ Exploit Third Party Advisory VDB Entry
https://www.exploit-db.com/exploits/42221/ Exploit Third Party Advisory VDB Entry
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2016-10033 US Government Resource
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