CVE-2026-35538Network attack vector

IMAP command injection via unsanitized search newlines

Published Apr 3, 2026 · Updated Apr 3, 2026

Argument injection in Roundcube Webmail before 1.5.14 and 1.6.0 through 1.6.13 allows remote authenticated users to alter IMAP commands. Mail-search handlers in program/actions/mail/search.php and send.php pass filter or Message-ID values containing CR/LF into IMAP SEARCH, permitting extra protocol commands. A valid webmail session and a crafted search or draft request are required; exploitation changes IMAP-side state or bypasses CSRF protections without reported data disclosure or service interruption.

CVSS severity3.1
Low
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Argument injection in Roundcube Webmail before 1.5.14 and 1.6.0 through 1.6.13 allows remote authenticated users to alter IMAP commands. Mail-search handlers in program/actions/mail/search.php and send.php pass filter or Message-ID values containing CR/LF into IMAP SEARCH, permitting extra protocol commands. A valid webmail session and a crafted search or draft request are required; exploitation changes IMAP-side state or bypasses CSRF protections without reported data disclosure or service interruption.

The record

CVE
CVE-2026-35538
Published
Apr 3, 2026
Updated
Apr 3, 2026
Vendor
Roundcube
Product
Roundcube Webmail
Classifications
CWE-88, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 3, 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=0 <1.5.14
  2. Affected versionversion=1.6.0 <1.6.14

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Roundcube · Roundcube Webmailversion=0 <1.5.14; version=1.6.0 <1.6.14

Published CVSS scores

3.1MITRECVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-88Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
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

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Your stack

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