CVE-2026-79663

Ech0 before 4.7.3 Stored XSS via RSS feed tag names

Published Aug 25, 2026 CVSS 4.0 · 4.8 Medium EPSS < 1% KEV · Not listed

Description

Ech0 before 4.7.3 contains a stored cross-site scripting vulnerability in the public RSS feed where tag names and markdown content are rendered without HTML escaping. Attackers with admin privileges can inject malicious tag names or raw HTML in echo content that executes as JavaScript in RSS readers that render HTML-type summaries, affecting anonymous subscribers and other users.

Analysis

Technical impact

Ech0 before version 4.7.3 contains a stored cross‑site scripting flaw in the public RSS feed. Tag names and markdown content are rendered without escaping, allowing an attacker with admin rights to inject JavaScript or malformed HTML into content that is later delivered to RSS readers.

Affected Systems

Ech0’s Ech0 application, versions earlier than 4.7.3 are vulnerable.

Risk and Exploitability

The CVSS score is 4.8, indicating moderate severity. Exploitation requires an adversary to have administrative privileges in order to inject malicious tag names or raw HTML. Once injected, the script executes in any RSS reader that renders the feed, affecting anonymous subscribers and other users who consume the feed. No exploit probability score is available and the vulnerability is not yet listed in CISA’s KEV catalog.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

lin-snow

Ech0

unaffected

Version	Status	Constraints
`0`	affected	< 4.7.3
`4.7.3`	unaffected	—

No data.

Vendor Product Versions

Ech0

Version	Status	Scheme	Platform
`—`	affected	—	—

Lin-snow

Ech0

Version	Status	Scheme	Platform
`[0,4.7.3)`	affected	semver	—
`4.7.3`	unaffected	semver	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade Ech0 to version 4.7.3 or later where the RSS tag rendering is properly escaped.
Restrict administrative access so that only trusted users can publish content that contains custom tag names or Markdown; enforce strict input validation for tag names and content.
Consider implementing a Content Security Policy on RSS readers or disabling HTML rendering for feed summaries to reduce the impact of any residual XSS content.

Generated by OpenCVE AI on August 25, 2026 at 12:23 UTC.

Tracking

Advisories

No advisories available

Metrics

Attack Vector Network

Attack Complexity Low

Privileges Required High

Attack Requirements None

User Interaction Passive

Vulnerable System Confidentiality Impact Low

Vulnerable System Integrity Impact Low

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact Low

Subsequent System Integrity Impact Low

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required High

Scope Changed

Confidentiality Impact Low

Integrity Impact Low

Availability Impact None

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.251% probability within 30 days)

Exploitation none

Automatable no

Technical Impact partial

References

Link	Providers
https://github.com/lin-snow/Ech0/security/advisories/GHSA-3v85-fqvh-7rxf
https://www.vulncheck.com/advisories/ech0-before-stored-xss-via-rss-feed-tag-names

History

Aug 27, 2026 6:00 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Aug 25, 2026 2:00 PM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Lin-snow Lin-snow ech0
Vendors & Products		Lin-snow Lin-snow ech0

Aug 25, 2026 11:45 AM Description updated. Title updated. First appearance in the feed. Weaknesses updated. Affected versions updated. Affected vendors updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		Ech0 before 4.7.3 contains a stored cross-site scripting vulnerability in the public RSS feed where tag names and markdown content are rendered without HTML escaping. Attackers with admin privileges can inject malicious tag names or raw HTML in echo content that executes as JavaScript in RSS readers that render HTML-type summaries, affecting anonymous subscribers and other users.
Title		Ech0 before 4.7.3 Stored XSS via RSS feed tag names
First Time appeared		Ech0 Ech0 ech0
Weaknesses		CWE-79
CPEs		cpe:2.3:a:ech0:ech0::::::::
Vendors & Products		Ech0 Ech0 ech0
References		https://github.com/lin-snow/Ech0/security/advisories/GHSA-3v85-fqvh-7rxf https://www.vulncheck.com/advisories/ech0-before-stored-xss-via-rss-feed-tag-names
Metrics		cvssV3_1 `{'score': 4.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N'}` cvssV4_0 `{'score': 4.8, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N'}`