CVE Intelligence
Medium Access control

CVE-2026-2559 — Post SMTP <= 3.8.0 - Missing Authorization to Authenticated (Subscriber+) Office 365 OAuth Configuration Overwrite

The Post SMTP plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the `handle_office365_oauth_redirect()` function in all versions up to, and including, 3.8.0. This is due to the function being hooked to `admin_init` without any `current_user_can()` check or nonce verification. This makes it possible for authenticated attackers, with Subscriber-level access and above, to overwrite the site's Office 365 OAuth mail configuration (access token, refresh token, and user email) via a crafted URL. The configuration option is used during wizard setup of Microsoft365 SMTP, only available in the Pro option of the plugin. This could cause an Administrator to believe an attacker-controlled Azure app is their own, and lead them to connect the plugin to the attacker's account during configuration after upgrading to Pro.

Published Mar 18, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Wordfence

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.3% (30-day exploitation probability)+4
  • Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.34%
ahead of 26% of scored CVEs · Oct 14, 2026
Affects
Saad Iqbal
Post SMTP – Complete Email Deliverability and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App
CVSS base
5.3
Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Saad Iqbal Post SMTP – Complete Email Deliverability and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes matching the vulnerability class (access control), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Saad Iqbal Post SMTP – Complete Email Deliverability and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App ≤ 3.8.0 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
5.3 CVSS 3.1 Medium 1.6 3.6 security@wordfence.com via NIST National Vulnerability Database
5.3 CVSS 3.1 Medium — — Wordfence via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N (score shown at the top: security@wordfence.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-862 · Missing Authorization

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.34%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Audit administrative actions and access to resources outside each user’s normal pattern.
web/proxy/WAF logsnetwork IDS/IPSauthentication logsapplication logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · saadiqbal/post smtp – complete email deliverability and smtp solution with email logs, alerts, backup smtp & mobile app
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • CVSS changed · 5.3
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Deferred
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVE published
    Mar 18, 2026 · Wordfence

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

4 on the record

Elsewhere on this site

Saad Iqbal
every CVE for this vendor
Access control
same class
CWE-862
other pages naming this weakness

Related CVEs (same products)

  • CVE-2024-13362 Freemius <= 2.10.1 - Reflected DOM-Based Cross-Site Scripting via url Parameter May 1, 2026
  • CVE-2026-3090 Post SMTP <= 3.8.0 - Unauthenticated Stored Cross-Site Scripting via 'event_type' Mar 18, 2026
  • CVE-2025-12887 Post SMTP – Complete SMTP Solution with Logs, Alerts, Backup SMTP & Mobile App <= 3.6.1 - Missing Authorization to Authenticated (Subscriber+) OAuth Token Update Dec 3, 2025
  • CVE-2025-11833 Post SMTP – Complete SMTP Solution with Logs, Alerts, Backup SMTP & Mobile App <= 3.6.0 - Missing Authorization to Account Takeover via Unauthenticated Email Log Disclosure Nov 1, 2025

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-2559 is "Post SMTP <= 3.8.0 - Missing Authorization to Authenticated (Subscriber+) Office 365 OAuth Configuration Overwrite", rated Medium. It affects Post SMTP – Complete Email Deliverability and SMTP Solution with Email Logs, Alerts, Backup SMTP & Mobile App (Saad Iqbal); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.3 describes technical severity. EPSS 0.34% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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