CVE-2026-16269Network attack vector

Unauthenticated API access via loose key comparison

Published Aug 8, 2026 · Updated Aug 8, 2026

Authentication bypass in Tribulant Software Newsletters before 4.16 allows remote attackers to perform privileged API actions. The API authentication path loosely compares a client-supplied key with the configured secret, allowing PHP type coercion to satisfy the check. Exploitation requires the optional JSON API to be enabled and permits subscriber-record changes or unauthorized email sending.

CVSS severityUnavailable
Unscored
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Authentication bypass in Tribulant Software Newsletters before 4.16 allows remote attackers to perform privileged API actions. The API authentication path loosely compares a client-supplied key with the configured secret, allowing PHP type coercion to satisfy the check. Exploitation requires the optional JSON API to be enabled and permits subscriber-record changes or unauthorized email sending.

The record

CVE
CVE-2026-16269
Published
Aug 8, 2026
Updated
Aug 8, 2026
Vendor
Tribulant Software
Product
Newsletters
Classifications
CWE-287, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <4.16

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Tribulant Software · Newslettersversion=0 <4.16

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo