CVE-2026-21640Network attack vector

Admin-console outage via unescaped INI interpolation

Published Jan 20, 2026 · Updated Jan 20, 2026

Format string injection in Revive Adserver 6.0.4 and earlier allows remote authenticated users to disable the admin console. The PEAR_Config INI-writing classes inadequately escape setting values, so an interpolation sequence such as ${{ triggers a fatal PHP error when the configuration is read. Administrator privileges are required to save the setting, and the resulting disruption is limited to the administrative interface.

CVSS severity2.7
Low
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Format string injection in Revive Adserver 6.0.4 and earlier allows remote authenticated users to disable the admin console. The PEAR_Config INI-writing classes inadequately escape setting values, so an interpolation sequence such as ${{ triggers a fatal PHP error when the configuration is read. Administrator privileges are required to save the setting, and the resulting disruption is limited to the administrative interface.

The record

CVE
CVE-2026-21640
Published
Jan 20, 2026
Updated
Jan 20, 2026
Vendor
Revive Adserver Project
Product
Revive Adserver
Classifications
CWE-134, T1499.004
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jan 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 20, 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=6 <=6.0.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Revive Adserver Project · Revive Adserverversion=6 <=6.0.4

Published CVSS scores

2.7NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N
2.7HackerOne CNACVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-134Use of Externally-Controlled Format String
T1499.004Application or System Exploitation

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

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Your stack

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