CVE-2026-48846Network attack vectorHinoki check available

Information disclosure via nested CSS URL sanitization bypass

Published May 25, 2026 · Updated May 25, 2026

Improper access control in Roundcube Webmail 1.6.0 through 1.6.15 and 1.7.0 allows remote attackers to disclose data via crafted email CSS. The rcube_utils::sanitize_css_block() parser checks only values beginning with url(), so a nested url() inside CSS var() survives sanitization and loads a remote resource. No Roundcube account or recipient click is required; rendering the message can contact an attacker-controlled URL, disclosing request metadata or bypassing remote-resource policy.

CVSS severity6.5
Medium
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Improper access control in Roundcube Webmail 1.6.0 through 1.6.15 and 1.7.0 allows remote attackers to disclose data via crafted email CSS. The rcube_utils::sanitize_css_block() parser checks only values beginning with url(), so a nested url() inside CSS var() survives sanitization and loads a remote resource. No Roundcube account or recipient click is required; rendering the message can contact an attacker-controlled URL, disclosing request metadata or bypassing remote-resource policy.

The record

CVE
CVE-2026-48846
Published
May 25, 2026
Updated
May 25, 2026
Vendor
Roundcube
Product
Roundcube Webmail
Classifications
CWE-669, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 25, 2026CVE publishedPublication date reported by the CVE source.
  2. May 25, 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=1.6.0 <1.6.16
  2. Affected versionversion=1.7.0 <1.7.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Roundcube · Roundcube Webmailversion=1.6.0 <1.6.16; version=1.7.0 <1.7.1

Published CVSS scores

6.5MITRECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-669Incorrect Resource Transfer Between Spheres
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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