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Vulnerability details: VCID-9yzy-78sh-xydu
Vulnerability ID VCID-9yzy-78sh-xydu
Aliases CVE-2026-31859
GHSA-fvwq-45qv-xvhv
Summary 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.
Status Published
Exploitability 0.5
Weighted Severity 6.2
Risk 3.1
Affected and Fixed Packages Package Details
Weaknesses (4)
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-116 Improper Encoding or Escaping of Output
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
epss 0.00041 https://api.first.org/data/v1/epss?cve=CVE-2026-31859
epss 0.00041 https://api.first.org/data/v1/epss?cve=CVE-2026-31859
cvssv3.1_qr MODERATE https://github.com/advisories/GHSA-fvwq-45qv-xvhv
cvssv4 6.9 https://github.com/craftcms/cms
generic_textual MODERATE https://github.com/craftcms/cms
cvssv4 6.9 https://github.com/craftcms/cms/commit/cc9921c14897ee2b592a431c2356af8a04ce4cfe
generic_textual MODERATE https://github.com/craftcms/cms/commit/cc9921c14897ee2b592a431c2356af8a04ce4cfe
cvssv3.1_qr MODERATE https://github.com/craftcms/cms/security/advisories/GHSA-fvwq-45qv-xvhv
cvssv4 6.9 https://github.com/craftcms/cms/security/advisories/GHSA-fvwq-45qv-xvhv
generic_textual MODERATE https://github.com/craftcms/cms/security/advisories/GHSA-fvwq-45qv-xvhv
ssvc Track https://github.com/craftcms/cms/security/advisories/GHSA-fvwq-45qv-xvhv
cvssv4 6.9 https://nvd.nist.gov/vuln/detail/CVE-2026-31859
generic_textual MODERATE https://nvd.nist.gov/vuln/detail/CVE-2026-31859
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2026-31859
https://github.com/craftcms/cms/commit/cc9921c14897ee2b592a431c2356af8a04ce4cfe
CVE-2026-31859 https://nvd.nist.gov/vuln/detail/CVE-2026-31859
GHSA-fvwq-45qv-xvhv https://github.com/advisories/GHSA-fvwq-45qv-xvhv
GHSA-fvwq-45qv-xvhv https://github.com/craftcms/cms/security/advisories/GHSA-fvwq-45qv-xvhv
No exploits are available.
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N Found at https://github.com/craftcms/cms
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N Found at https://github.com/craftcms/cms/commit/cc9921c14897ee2b592a431c2356af8a04ce4cfe
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N Found at https://github.com/craftcms/cms/security/advisories/GHSA-fvwq-45qv-xvhv
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

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passive

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Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2026-03-12T14:00:11Z/ Found at https://github.com/craftcms/cms/security/advisories/GHSA-fvwq-45qv-xvhv
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N Found at https://nvd.nist.gov/vuln/detail/CVE-2026-31859
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

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Exploit Prediction Scoring System (EPSS)
Percentile 0.12811
EPSS Score 0.00041
Published At June 11, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-06-11T16:44:50.022632+00:00 Vulnrichment Import https://github.com/cisagov/vulnrichment/blob/develop/2026/31xxx/CVE-2026-31859.json 38.6.0