CVE-2026-35538: Roundcube Webmail Unsanitized IMAP SEARCH Command Arguments Vulnerability

LOW
Advisory Identifier: GHSA-8jr8-v43g-5c57
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CVSS 3.1
CWE-88
Published
Advisory Summary

CVE-2026-35538 is a LOW (CVSS 3.1) unsanitized imap search command arguments vulnerability (CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')) affecting Roundcube Webmail libraries in the Packagist ecosystem. The issue involves unsanitized imap search command arguments. Remediation is available by upgrading affected packages to version 1.7-rc5.

CVE-2026-35538 at a Glance

CVE Identifier CVE-2026-35538
GHSA Identifier GHSA-8jr8-v43g-5c57
Severity LOW
CVSS v3.1 Base Score 3.1
CWE Classification CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
Affected Product Roundcube Webmail
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 3.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-35538

To remediate this vulnerability, upgrade all affected Roundcube Webmail dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

roundcube/roundcubemail fixed: 1.7-rc5 
Upgrade roundcube/roundcubemail to 1.7-rc5
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for roundcube/roundcubemail

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-35538, inspect your project dependencies for Roundcube Webmail:

inspect dependencies for roundcube/roundcubemail

Analyze the terminal output to locate any version of Roundcube Webmail in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.7-rc5), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection'), where the product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string. In Roundcube Webmail, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. Unsanitized IMAP SEARCH command arguments could lead to IMAP injection or CSRF bypass during mail search.

CVE-2026-35538 Affected Roundcube Webmail Versions

1 component(s)
Fixed Versions:
1.7-rc5
Product / Package Ecosystem Affected Versions Fixed Version
roundcube/roundcubemail
 Packagist
≥ 1.7-beta
< 1.7-rc5
1.7-rc5

References

NVD — CVE-2026-35538 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-35538
Security Fix Commit FIX COMMIT
https://github.com/roundcube/roundcubemail/commit/5fe8a69956a9683a4269f3ad2a68e18deebf8a15
Security Fix Commit FIX COMMIT
https://github.com/roundcube/roundcubemail/commit/7daf5aa9c190ccc75bb31672d8fee9938877fd64
Security Fix Commit FIX COMMIT
https://github.com/roundcube/roundcubemail/commit/b18a8fa8e81571914c0ff55d4e20edb459c6952c
Roundcube Webmail Source Repository REPOSITORY
https://github.com/roundcube/roundcubemail
Roundcube Webmail Release RELEASE
https://github.com/roundcube/roundcubemail/releases/tag/1.5.14
Roundcube Webmail Release RELEASE
https://github.com/roundcube/roundcubemail/releases/tag/1.6.14
Roundcube Webmail Release RELEASE
https://github.com/roundcube/roundcubemail/releases/tag/1.7-rc5
Roundcube Webmail Security Information SECURITY
https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14

Frequently Asked Questions

What is CVE-2026-35538?
CVE-2026-35538 is a security vulnerability in Roundcube Webmail involving Unsanitized IMAP SEARCH command arguments under CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection').
Which Roundcube Webmail versions are affected?
Affected versions include releases prior to 1.7-rc5 across affected packages: roundcube/roundcubemail.
What version fixes CVE-2026-35538?
Upgrading to 1.7-rc5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is roundcube/roundcubemail affected?
Yes, roundcube/roundcubemail is affected in releases prior to 1.7-rc5. Upgrade your dependency to 1.7-rc5 or later.
What is the CVSS score of CVE-2026-35538?
CVE-2026-35538 has a CVSS v3.1 base score of 3.1 (LOW) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2026-35538?
CVE-2026-35538 is classified under CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection') (The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.).
How can I check Packagist dependencies for CVE-2026-35538?
Run the dependency tree command: 'inspect dependencies for roundcube/roundcubemail'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-8jr8-v43g-5c57",
  "modified" : "2026-04-04T06:50:35Z",
  "published" : "2026-04-03T06:31:32Z",
  "aliases" : [ "CVE-2026-35538" ],
  "summary" : "Roundcube Webmail: Unsanitized IMAP SEARCH command arguments",
  "details" : "An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. Unsanitized IMAP SEARCH command arguments could lead to IMAP injection or CSRF bypass during mail search.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "roundcube/roundcubemail"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.7-beta"
      }, {
        "fixed" : "1.7-rc5"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-35538"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/roundcube/roundcubemail/commit/5fe8a69956a9683a4269f3ad2a68e18deebf8a15"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/roundcube/roundcubemail/commit/7daf5aa9c190ccc75bb31672d8fee9938877fd64"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/roundcube/roundcubemail/commit/b18a8fa8e81571914c0ff55d4e20edb459c6952c"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/roundcube/roundcubemail"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/roundcube/roundcubemail/releases/tag/1.5.14"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/roundcube/roundcubemail/releases/tag/1.6.14"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/roundcube/roundcubemail/releases/tag/1.7-rc5"
  }, {
    "type" : "WEB",
    "url" : "https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-88" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-04T06:50:35Z",
    "nvd_published_at" : "2026-04-03T05:16:21Z"
  }
}