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.

CVSS: 6.1Mediumscored by the publisher (CNA)
Exploited in the wild: Yes, in CISA KEV since 26 Oct 2023CISA deadline for US federal agencies: 16 Nov 2023
EPSS: 76.3%chance of exploitation in the next 30 daystop 0.5% of scored CVEsFIRST score of 11 Nov 2026
Fix: Fixed in 1.4.15, 1.5.5, 1.6.4per the vendor; 1 more listed below
Published: 18 Oct 2023analysed here 12 Nov 2026

Do first. Upgrade to a fixed release: 1.4.15, 1.5.5, 1.6.4, 1.5.15.

Summary

Triage

Attack surface: Client-side
Exploitable: At runtime
Attack vector: network
Weakness: CWE-79 Cross-Site Scripting (XSS)
Can a WAF block it?: Yes. See why

The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.

Affected products

Product	Affected versions	Vendor says fixed in
roundcubefrom the Bitnami advisory, via OSV	< 1.4.15>= 1.5.0 and < 1.5.5>= 1.6.0 and < 1.6.4Vendor says fixed in: 1.4.15, 1.5.5, 1.6.4	1.4.151.5.51.6.4
Roundcube Roundcubemail	>= 1.6.0 and < 1.6.3>= 1.5.0 and < 1.5.4>= 1.4.0 and < 1.5.14Vendor says fixed in: 1.6.4, 1.5.5, 1.5.15	1.6.41.5.51.5.15

As published in the CVE Program record, and, for products that ship the affected component, in the advisory named beside them. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

Products named in our analysis

roundcube:webmail
debian:debian_linux
fedoraproject:fedora

Fix and mitigation

WAF and other mitigations

Can a WAF block it? Yes. The attack is delivered via an HTML email message with a crafted SVG document, which is processed by the webmail interface. A WAF could partially detect unusual SVG content or script tags embedded in emails, but distinguishing malicious SVG from legitimate HTML email content is challenging. A custom WAF rule can filter HTML email messages containing crafted SVG documents, but attackers can vary the request. No tracked WAF vendor has published a rule for this CVE yet.

What a custom rule would match: HTML email messages containing crafted SVG documents

Also consider: patch · custom WAF rule · CSP · output encoding

Based on an AI reading of the CVE description, and no vendor rule found yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.

Remediation steps (AI-written)

Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.

Exploitation evidence

CISA KEV catalog: Listed since 26 Oct 2023.
CISA due date: 16 Nov 2023, the remediation deadline for US federal agencies
CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Public exploit code: None on record in Exploit-DB, Metasploit, Nuclei templates or PoC-in-GitHub.
CISA SSVC: exploitation active, automatable no, technical impact totalAssessed by CISA 15 Nov 2023 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.

Timeline

18 Oct 2023Published
26 Oct 2023Added to CISA KEV (exploited in the wild)7 days later
15 Nov 2023CISA SSVC assessment: exploitation active21 days later
16 Nov 2023CISA remediation due date (US federal agencies)same day later
21 Oct 2025CVE record last updated706 days (about 2 years) later
12 Nov 2026Analysed by vulneraibility.com387 days (about 1 year) later

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Metric	Value	What it means
Attack vector	NetworkReachable over the internet or any routable network.	Reachable over the internet or any routable network.
Attack complexity	LowRepeatable attack, no special conditions.	Repeatable attack, no special conditions.
Privileges required	NoneThe attacker needs no prior access.	The attacker needs no prior access.
User interaction	RequiredA victim must click, open or otherwise cooperate.	A victim must click, open or otherwise cooperate.
Scope	ChangedImpact crosses a security boundary into other components.	Impact crosses a security boundary into other components.
Confidentiality	LowPartial data disclosure.	Partial data disclosure.
Integrity	LowLimited modification possible.	Limited modification possible.
Availability	NoneThe service stays up.	The service stays up.

Common questions

Is CVE-2023-5631 being exploited?

Yes. CVE-2023-5631 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.

How severe is CVE-2023-5631?

CVE-2023-5631 is rated Medium with a CVSS score of 6.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2023-5631?

Yes. A fix has been recorded for CVE-2023-5631. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2023-5631 affect?

CVE-2023-5631 affects roundcube:webmail, debian:debian_linux, fedoraproject:fedora. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

References

NVD CVE.org CVE Details Source

16 references in the CVE record, grouped by the tags the record gives them.

Where the data on this page comes from

CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
NVD: CVSS and CPE data
CISA KEV catalog: exploitation, date added, due date
CISA Vulnrichment (ADP): SSVC decision points
FIRST EPSS: exploit probability and percentile

Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.

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