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VulnerabilityCVE-2023-5631Published 2023-10-18

CVE-2023-5631 — Roundcube Webmail

mediumCISA KEV

As of 2025-10-30, CVE-2023-5631 is a MEDIUM-severity vulnerability in Roundcube Webmail, CVSS v3.1 6.1, EPSS 83.4% (99.2th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-10-26), with a US federal remediation deadline of 2023-11-16. No Threadlinqs-tracked threat campaign has been attributed to CVE-2023-5631 as of 2025-10-30; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

CVSS v3.1
6.1/10Medium
EPSS
83.4%Higher than 99.2% of scored CVEs
CISA KEV
ListedAdded · due 2023-11-16
Tracked threats
0None linked yet
Priority
9/10Threadlinqs triage score
Published
Updated 2025-10-30
CVSS v3.1 6.1 (MEDIUM) · EPSS 83.4% (higher than 99.2% of all scored CVEs) · Priority 9/10 · Published 2023-10-18

Last updated:

What is CVE-2023-5631?

Roundcube before 1.4.15, 1.5.x before 1.5.5, and 1.6.x before 1.6.4 allows stored XSS via an HTML e-mail message with a crafted SVG document because of program/lib/Roundcube/rcube_washtml.php behavior. This could allow a remote attacker to load arbitrary JavaScript code.

The record classifies CVE-2023-5631 under weakness class CWE-79. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first. 5 affected-product entries are recorded, across 3 vendors, listed below. The identifier was first published 1083 days ago.

Severity and exploitation probability

CVSS v3.1 base score
6.1 — MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS (FIRST)
83.4% probability of exploitation in the next 30 days, higher than 99.2% of all scored CVEs
CISA KEV
Listed since 2023-10-26, federal remediation deadline 2023-11-16
Threadlinqs priority
9/10 — CISA KEV-listed, which Threadlinqs floors at 9
Published
2023-10-18, last modified 2025-10-30

Is CVE-2023-5631 being exploited?

CISA added CVE-2023-5631 to the Known Exploited Vulnerabilities catalog on 2023-10-26, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2023-11-16 under BOD 22-01. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.

Affected products and versions

How to fix CVE-2023-5631

The record marks a vendor fix as available for CVE-2023-5631. Patch reference: https://github.com/roundcube/roundcubemail/releases/tag/1.6.4. Vendor advisory: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1054079. Because CVE-2023-5631 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2023-11-16. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2023-5631

No threat campaign in the Threadlinqs corpus currently references CVE-2023-5631, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

Sources

Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.