HIGH
CVE-2021-34551
CWE-434Published: June 16, 2021· Updated: Jun 17, 2026
8.1
CVSS v3.1
Official Description
PHPMailer before 6.5.0 on Windows allows remote code execution if lang_path is untrusted data and has a UNC pathname.
Technical Analysis
CVE-2021-34551 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.1.
CVSS v3.1 Vector Breakdown
Exploitability
Attack VectorNetwork
Attack ComplexityHigh
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected Vendors & Products
Fedora1 product(s)
fedora
Microsoft1 product(s)
windows
phpmailer_project1 product(s)
phpmailer
Source: NVD CPE · 4 total CPE entries
Exploit & PoC Resources
NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.
Official Patches & Advisories
All References (6)
→
https://github.com/PHPMailer/PHPMailer/blob/master/SECURITY.mdIssue Tracking · Third Party Advisory
→
https://github.com/PHPMailer/PHPMailer/blob/master/SECURITY.mdIssue Tracking · Third Party Advisory
Quick Facts
CVE IDCVE-2021-34551
CVSS Score8.1 / 10
SeverityHIGH
WeaknessCWE-434
CISA KEVNo
Affected3 vendor(s)
PublishedJun 16, 2021
Related CVEs (CWE-434)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-34551 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.