CVE-2021-4422: POST SMTP Mailer <= 2.0.20 - Cross-Site Request Forgery Bypass
Noroxi assessment
Priority: Monitor (action score 17/100)
- 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: 0.54% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
- According to the record, no fixed version is available yet.
Low priority for now. Update when a fix is released; follow the vendor's advisory.
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
The POST SMTP Mailer plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 2.0.20. This is due to missing or incorrect nonce validation on the handleCsvExport() function. This makes it possible for unauthenticated attackers to trigger a CSV export via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
- Published
- Jul 12, 2023
- Updated
- Jun 17, 2026
- EPSS
- 0.5% · 45th percentile
- CWE
- CWE-352
Report tools
Action score
17
Monitor
Low priority for now.
- CVSS
- 17 / 40 · 4.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.5%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 4.3
- CNA · Wordfence
- 4.3
- agree
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Is Post SMTP – Complete Email Delivery and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App on your site?
WP Lens reads your site's plugin, theme and WordPress versions from the outside and matches them to known vulnerabilities. Works without an account.
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 |
|---|---|---|
| wpexperts | post smtp | cpe:2.3:a:wpexperts:post_smtp |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- wpexperts post smtpup to 2.0.20 inclusive
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Wordfence). Independent of NVD's CPE analysis and usually ahead of it.
saadiqbal Post SMTP – Complete Email Deliverability and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App
- up to and including 2.0.20affected · semver
Same product
wpexperts: all recordsOther highest-scoring records for the same primary product.
- CVE-2023-6875POST SMTP Mailer – Email log, Delivery Failure Notifications and Best Mail SMTP for WordPress <= 2.8.7 - Authorization Bypass via type connect-app API66This week
- CVE-2023-52233WordPress POST SMTP Mailer plugin <= 2.8.6 - Broken Access Control on API vulnerability39Monitor
- CVE-2025-22800WordPress Post SMTP plugin <= 2.9.11 - Broken Access Control vulnerability35Monitor
Published before and after this one in the same product
- ← EarlierCVE-2022-2352Sep 26, 2022 · Post SMTP < 2.1.7 - Admin+ Blind SSRF28Monitor
- ← EarlierCVE-2023-3082Jul 12, 2023 · Post SMTP <= 2.5.7 - Unauthenticated Stored Cross-Site Scripting via Email24Monitor
- Later →CVE-2023-3179Jul 17, 2023 · POST SMTP Mailer < 2.5.7 - Account Takeover via CSRF35Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
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.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- Jerome Bruandetfinder
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.
- A user must open a link or visit a page.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- low · data or configuration can be modified
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- Low
- Availability impact
- None
Weakness class (CWE)
CWE-352 · Cross-Site Request Forgery (CSRF)CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
nvd-primary
Root cause
State-changing requests rely on the session cookie the browser sends automatically; nothing verifies that the request came from the user’s own page.
The bug in code
The whole CWE-352 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
app.use(session({ cookie: { httpOnly: true } }));
app.post("/account/address", updateAddress);Fixed
app.use(session({ cookie: { httpOnly: true, sameSite: "lax" } }));
app.post("/account/address", csrfProtection, updateAddress);Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Change log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
Show all references (8 more)Show less
- blog.nintechnet.com/more-wordpress-plugins-and-themes-vulnerable-to-csrf-attacks/
- blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-1/
- blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-2/
- blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-3/
- blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-4/
- blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-5/
- plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=2473579%40post-smtp&new=2473579%40post-smtp&sfp_email=&sfph_mail=
- www.wordfence.com/threat-intel/vulnerabilities/id/e018ca7c-06dd-4d40-91d4-4ed188b8aaf2?source=cve
Vendor advisories and official records. Exploit/PoC links are deliberately left out.