vulnerability / NVI-00000064 / Revision 5
CVE-2016-10033
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.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
9.8 CRITICAL (3.1)
CISA-ADP severity and vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H; not a measure of customer compromise.
Listed
CISA lists known exploitation. This does not establish exploitation of your system.
As of · CISA
7.5 HIGH (2.0)
nvd@nist.gov severity; no combined Null risk score.
9.8 CRITICAL (3.1)
nvd@nist.gov severity; no combined Null risk score.
9.8 CRITICAL (3.1)
134c704f-9b21-4f2e-91b3-4a467353bcc0 severity; no combined Null risk score.
99.714%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.99952. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
n/a
source listedn/a
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.
phpmailer/phpmailer
source listedECOSYSTEM: introduced 5.0.0; fixed 5.2.18
### Impact The `mailSend` function in the default `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. ### Patches Fixed in 5.2.18 ### Workarounds Filter and validate user input before passing it to internal functions. ### References https://nvd.nist.gov/vuln/detail/CVE-2016-10033 Related to a follow-on issue in https://nvd.nist.gov/vuln/detail/CVE-2016-10045 ### For more information If you have any questions or comments about this advisory: * Open a private issue in the PHPMailer project
PHP PHPMailer
source listedThe linked source does not supply a complete affected-version range here.
CISA does not supply a complete application-specific affected range here. Follow the linked vendor advisory for version and configuration prerequisites.
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
- vendor patch
The original advisory lists fixed boundaries 5.2.18 for phpmailer/phpmailer. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
- investigate
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. CISA
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
- CISA catalog date-added and due-date fields are not the original vulnerability disclosure date or universal legal deadlines.
- NVD lastModified does not establish freshness of every associated CPE record.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- CVE-2016-10033 ↗
CVE Program / attributed CNA and ADP · cna record
Observed . CVE content: copyright The MITRE Corporation; CVE Terms of Use and license apply. CNA and ADP publishers retain separate attribution.
- GHSA-5f37-gxvh-23v6 ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
- CVE-2016-10033 ↗
CISA · official catalog
Observed . CISA KEV; CC0 1.0. Catalog assertions are not evidence of customer compromise.
- CVE-2016-10033 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
- CVE-2016-10033 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 5 ·
Source facts changed; compare the preserved prior revision.
- Revision 4 ·
Source facts changed; compare the preserved prior revision.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.