EUVD-2026-62415Severity by source
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Network-delivered stored XSS requiring low-privilege auth and passive victim interaction; scope change applies because session impact crosses to the victim user's security context.
Primary rating from Vendor (Fluid Attacks).
CVSS VectorVendor: Fluid Attacks
Lifecycle Timeline
3DescriptionCVE.org
HumHub Community Edition 1.18.4 and 1.18.4-pl1 contain a stored Cross-Site Scripting (XSS) vulnerability in the oEmbed confirmation rendering workflow.
AnalysisAI
Stored XSS in HumHub Community Edition 1.18.4 and 1.18.4-pl1 allows authenticated low-privilege users to inject arbitrary HTML and JavaScript into the oEmbed confirmation prompt rendered for other users. The attacker-controlled URL prefix was passed unencoded into the HTML consent dialog via Html::tag() in UrlOembed.php, and a secondary code path flaw allowed confirmation content to flow through a CSP nonce injection routine - meaning embedded markup could acquire a valid nonce and bypass Content Security Policy. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a valid authenticated session in HumHub with at least low-privilege content-posting rights (PR:L per the CVSS 4.0 vector). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 4.0 score of 7.4 is grounded in confirmed high confidentiality and integrity impact on the vulnerable system (VC:H/VI:H), reflecting realistic session hijacking and account takeover outcomes. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Upstream fix is available via GitHub PR #8373 (https://github.com/humhub/humhub/pull/8373); a tagged released patched version is not independently confirmed from the available input data - organizations should monitor the HumHub releases page at https://github.com/humhub/humhub for the next tagged version incorporating this fix. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all HumHub Community Edition instances running versions 1.18.4 or 1.18.4-pl1 and document which users have authentication access. …
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SQL injection vulnerability in the actionIndex function in protected/modules_core/notification/controllers/ListControlle
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Stored cross-site scripting in HumHub 1.18.4 lets a Space administrator embed arbitrary HTML or JavaScript into the dele
Reflected cross-site scripting in HumHub Community Edition 1.18.4 allows a low-privileged attacker to inject arbitrary J
Broken access control in HumHub 1.13.0 through 1.18.2 lets any authenticated user delete every member of any Space, rega
HumHub Calendar module versions prior to 1.8.11 contain a stored XSS vulnerability in Event Types that allows attackers
Generation of Error Message Containing Sensitive Information in HumHub GmbH & Co. Rated medium severity (CVSS 6.9), this
Cross-site scripting in HumHub 1.18.0's Button component allows unauthenticated attackers to inject and execute maliciou
A Reflected Cross Site Scripting (XSS) Vulnerability was discovered in /s/adada/cfiles/upload in Humhub 1.3.10 Community
Same weakness CWE-79 – Cross-site Scripting (XSS)
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External POC / Exploit Code
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