CVE-2026-16504Network attack vector

Instance takeover via static secrets and cleartext transport

Published Jul 31, 2026 · Updated Jul 31, 2026

Insecure defaults in VPS.org Zulip Template allow remote attackers to forge sessions, access the database, and intercept traffic. The static template instantiates secret_key: changeme, the zulip database password, and DISABLE_HTTPS=True without deployment-specific randomization or transport hardening. The public key enables remote attackers to forge sessions without credentials; unchanged defaults also expose database access and let man-in-the-middle attackers intercept credentials and session data.

CVSS severity9.8
Critical
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insecure defaults in VPS.org Zulip Template allow remote attackers to forge sessions, access the database, and intercept traffic. The static template instantiates secret_key: changeme, the zulip database password, and DISABLE_HTTPS=True without deployment-specific randomization or transport hardening. The public key enables remote attackers to forge sessions without credentials; unchanged defaults also expose database access and let man-in-the-middle attackers intercept credentials and session data.

The record

CVE
CVE-2026-16504
Published
Jul 31, 2026
Updated
Jul 31, 2026
Vendor
VPS.org
Product
Zulip Template
Classifications
CWE-1393, CWE-1188, CWE-321, T1550.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 31, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 31, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=N/A

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

VPS.org · Zulip Templateversion=N/A

Published CVSS scores

9.8CISA ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1393Use of Default Password
CWE-1188Initialization of a Resource with an Insecure Default
CWE-321Use of Hard-coded Cryptographic Key
T1550.004Use Alternate Authentication Material: Web Session Cookie

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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