CVE-2016-10033
PHP — PHPMailer Command Injection Vulnerability
PHP · CWE-88 · in CISA KEV since 2025-07-07
EVRS 88 of 100 Immediate
Out-of-Band / Urgent Remediation
Rank 168 of 2,960 tracked
Why it scores 88
Evidence available: 6 of 7 signalsListed in the CISA KEV catalog, and an EPSS probability of 0.997.
- CISA KEVApplied
- RansomwareDid not apply
- Vendor exploitationDid not apply
- EPSSApplied
- Microsoft Exploitability IndexNot applicable
- Pre-patch disclosureNo data
- KEV recencyDid not apply
- CVSSApplied
The band answers “how soon”, not “how bad”. No data for: Pre-patch disclosure. Why some signals show no data
Fix
Patch or fixed version identifiedCISA required action
- This vulnerability could affect an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see
- github.com/…/GHSA-5f37-gxvh-23v6
- nvd.nist.gov/…/CVE-2016-10033
Fixed in
- phpmailer/phpmailer
5.2.18
Affected versions
- phpmailer/phpmailer (composer)
affected >= 5.0.0, < 5.2.18, fixed in 5.2.18
Remediation
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Fixed versions from NVD and GitHub. Affected packages also in GitHub Advisory GHSA-5f37-gxvh-23v6 (CC BY 4.0).
Evidence
Each value with its source| Measure | Value | Source |
|---|---|---|
| CVSS base scoreHow severe the flaw is in itself. It does not say how likely an attack is. | 9.8 | NVD |
| FIRST EPSSFIRST's estimate of the chance this is exploited in the next 30 days, and how that ranks against all CVEs. | 0.997 (99.95th pctl) | FIRST EPSS |
| Actively exploitedWhether a source of record has confirmed attacks using it in the wild. | Confirmed | CISA KEV |
| Ransomware campaign useWhether CISA has seen ransomware operators use it. | Unknown or none | CISA KEV |
| CISA remediation deadlineThe date US federal agencies must have fixed or mitigated it. | 2025-07-28 · KEV since 2025 · listed over a year | CISA KEV |
| Public exploit moduleA module existing is not the same as active exploitation. | Public module exists | Metasploit |
| EUVD cross-referenceENISA's record: CVSS 9.8 (v3.1), assigned by mitre. | Listed | ENISA EUVD |
Description
NVDThe 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.
What CISA says to do
- This vulnerability could affect an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see
- github.com/…/GHSA-5f37-gxvh-23v6
- nvd.nist.gov/…/CVE-2016-10033
Public module
Metasploit lists the best-ranked (average) of 2 public modules for this CVE: WordPress PHPMailer Host Header Command Injection (unix/webapp/wp_phpmailer_host_header). A module existing is not the same as active exploitation; see metasploit.com.