CVE-2023-43770Known exploitationPublic exploitNetwork attack vector

Cross-site scripting via unsanitized link-reference labels

Published Sep 22, 2023 · Updated Oct 21, 2025

Cross-site scripting in Roundcube Webmail allows remote attackers to execute script in a user's browser through a crafted plain-text email. The link-reference regexes in rcube_string_replacer.php accepted angle brackets in bracketed labels, allowing script markup to survive conversion to HTML. A user must view the crafted message; the injected script then runs in the Roundcube origin and can access or alter webmail data available to that session.

CVSS severity6.1
Medium
EPSS probability58.48%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Roundcube Webmail allows remote attackers to execute script in a user's browser through a crafted plain-text email. The link-reference regexes in rcube_string_replacer.php accepted angle brackets in bracketed labels, allowing script markup to survive conversion to HTML. A user must view the crafted message; the injected script then runs in the Roundcube origin and can access or alter webmail data available to that session.

The record

CVE
CVE-2023-43770
Published
Sep 22, 2023
Updated
Oct 21, 2025
Vendor
Debian
Product
Debian GNU/Linux
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 22, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 21, 2025Record 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=10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Debian · Debian GNU/Linuxversion=10
Roundcube · Roundcube Webmailversion=0 <1.4.14; version=1.5.0 <1.5.4; version=1.6.0 <1.6.3

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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.

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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 exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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