Inclusion of Functionality from Untrusted Control Sphere in PHPMailer/PHPMailer
Noroxi assessment
Priority: Monitor (action score 33/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 2.2% (FIRST EPSS); higher than 82.6% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
- Fixed version: libphp-phpmailer (Debian:12) 6.6.3-1; phpmailer/phpmailer (Packagist) 6.5.0.
Low priority for now. Upgrade to libphp-phpmailer (Debian:12) 6.6.3-1; phpmailer/phpmailer (Packagist) 6.5.0 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
PHPMailer 6.4.1 and earlier contain a vulnerability that can result in untrusted code being called (if such code is injected into the host project's scope by other means). If the $patternselect parameter to validateAddress() is set to 'php' (the default, defined by PHPMailer::$validator), and the global namespace contains a function called php, it will be called in preference to the built-in validator of the same name. Mitigated in PHPMailer 6.5.0 by denying the use of simple strings as validator function names.
- Published
- Jun 17, 2021
- Updated
- Jun 17, 2026
- EPSS
- 2.3% · 83th percentile
- CWE
- CWE-829
Report tools
Action score
33
Monitor
Low priority for now.
- CVSS
- 32 / 40 · 8.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 2.3%
CNA vs NVD score
- NVD
- 8.1
- CNA · @huntrdev
- 8.1
- agree
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| phpmailer project | phpmailer | cpe:2.3:a:phpmailer_project:phpmailer |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- fedoraproject fedora33
- fedoraproject fedora34
- phpmailer project phpmailerup to 6.4.1 inclusive
Versions reported by the vendor
Affected version ranges reported by the assigning authority (@huntrdev). Independent of NVD's CPE analysis and usually ahead of it.
PHPMailer PHPMailer
- unspecified and later · before 6.5.0affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | libphp-phpmailer | before 6.6.3-1 | 6.6.3-1 |
| Packagist | phpmailer/phpmailer | before 6.5.0 | 6.5.0 |
Same product
phpmailer project: all recordsOther highest-scoring records for the same primary product.
- CVE-2016-10033The mailSend function in the isMail transport in PHPMailer before 5.2.18 might allow remote attackers to pass extra parameters to the mail cKEV99Now
- CVE-2016-10045The isMail transport in PHPMailer before 5.2.20 might allow remote attackers to pass extra parameters to the mail command and consequently e68This week
- CVE-2020-36326PHPMailer 6.1.8 through 6.4.0 allows object injection through Phar Deserialization via addAttachment with a UNC pathname.40Plan
- CVE-2018-19296PHPMailer before 5.2.27 and 6.x before 6.0.6 is vulnerable to an object injection attack.36Monitor
- CVE-2021-34551PHPMailer before 6.5.0 on Windows allows remote code execution if lang_path is untrusted data and has a UNC pathname.33Monitor
- CVE-2020-13625PHPMailer before 6.1.6 contains an output escaping bug when the name of a file attachment contains a double quote character.31Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:libphp-phpmailer | 6.6.3-1 · Debian:12 | Package registry (OSV) |
| Packagist:phpmailer/phpmailer | 6.5.0 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-829 · Inclusion of Functionality from Untrusted Control SphereCVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Code InclusionCAPEC-175likelihood: Medium · Very High
- Serialized Data External LinkingCAPEC-201likelihood: High · High
- DTD InjectionCAPEC-228Medium
- Local Code InclusionCAPEC-251Medium
- PHP Local File InclusionCAPEC-252Medium
- Remote Code InclusionCAPEC-253
- Force Use of Corrupted FilesCAPEC-263Medium
- Open-Source Library ManipulationCAPEC-538likelihood: Low · High
ATT&CK techniques
- Process InjectionT1055
- Browser ExtensionsT1176
- Supply Chain Compromise: Software Dependencies and Development ToolsT1195.001
- Server Software Component: IIS ComponentsT1505.004
- Server Software Component: Terminal Services DLLT1505.005
- Hijack Execution Flow: Dynamic Linker HijackingT1574.006
- Hijack Execution Flow: KernelCallbackTableT1574.013
- Reflective Code LoadingT1620
Change log
- Fix✗ → ✓
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References
Show all references (3 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.