Is CVE-2026-31859 in the CISA KEV catalog?

No. CVE-2026-31859 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-31859?

CVE-2026-31859 has a CVSS v3 base score of 6.1 (MEDIUM).

What is the EPSS score for CVE-2026-31859?

CVE-2026-31859 has an EPSS score of 0.18% (8th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-31859?

Upgrade craft cms to 5.9.7 or later.

CVE & CISA-KEV Catalog

CVE-2026-31859

MEDIUM

6.1

CVSS v3

NVD

Description

Craft is a content management system (CMS). The fix for CVE-2025-35939 in craftcms/cms introduced a strip_tags() call in src/web/User.php to sanitize return URLs before they are stored in the session. However, strip_tags() only removes HTML tags (angle brackets) -- it does not inspect or filter URL schemes. Payloads like javascript:alert(document.cookie) contain no HTML tags and pass through strip_tags() completely unmodified, enabling reflected XSS when the return URL is rendered in an href attribute. This vulnerability is fixed in 5.9.7 and 4.17.3.

CWE-79Cross-Site Scripting (XSS)CWE-116

How to fix

Remediation Available

craft cmsNVD

Affected:>= 5.7.5, < 5.9.7Fixed in:5.9.7CVE-2026-31859derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.18%probability of exploitation in 30 days

8thpercentile

Low risk: more likely to be exploited than 8% of all known CVEs.

References

Patch1

github.com

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-17.