Fathom Lite 1.3.1 Stored XSS via /collect Endpoint
Published Jul 23, 2026
5.1
MEDIUMCVSS 4.0
EPSS 0.27%
Description
Fathom Lite through 1.3.1 contains a stored cross-site scripting vulnerability in the analytics collection endpoint that allows unauthenticated attackers to inject a javascript: URI into the Top Pages dashboard by supplying a crafted hostname and pathname to the unauthenticated /collect endpoint. The parseHostname and parsePathname functions perform no URI scheme validation, allowing a javascript: hostname combined with a newline-prefixed pathname to be stored and later rendered as an anchor href in the authenticated dashboard without sanitization, enabling session hijacking and full account takeover when an operator clicks the poisoned entry.
Affected products
-
- Version 0StatusaffectedConstraints<=1.3.1
- Version
No data.
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
1 other source (NVD) ▾
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/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
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
PoCAutomatable
NoTechnical Impact
PartialDecision
n/aAssessed Jul 23, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 2, 2026.
Score over time
Jul–Oct 2026- EPSS v5
Percentile over time
- EPSS v5
Table of values (2 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 2, 2026 | 0.27% (0.00273) | 17.83th | v5 (v2026.06.15) |
| Jul 24, 2026 | 0.16% (0.00160) | 5.63th | v5 (v2026.06.15) |
References (2)
- https://github.com/geo-chen/oss/blob/main/fathom.md technical-descriptionexploit
- https://www.vulncheck.com/advisories/fathom-lite-stored-xss-via-collect-endpoint third-party-advisory
| Link | Providers | Tags |
|---|---|---|
| https://github.com/geo-chen/oss/blob/main/fathom.md | technical-descriptionexploit | |
| https://www.vulncheck.com/advisories/fathom-lite-stored-xss-via-collect-endpoint | third-party-advisory |
Change history (0)
No recorded changes yet.