Filename disclosure via wildcard SSE origin policy
Published May 26, 2026 · Updated May 26, 2026
Information disclosure in Algernon before 1.17.7 allows remote attackers to read live filenames through the auto-refresh SSE endpoint. MustServe passes a literal wildcard to GenFileChangeEvents, which writes it to Access-Control-Allow-Origin without comparing the request Origin. Auto-refresh must be enabled and a developer must visit an attacker-controlled page; the resulting EventSource exposes the filename stream but does not alter data or interrupt service.
Summary
What happened
Information disclosure in Algernon before 1.17.7 allows remote attackers to read live filenames through the auto-refresh SSE endpoint. MustServe passes a literal wildcard to GenFileChangeEvents, which writes it to Access-Control-Allow-Origin without comparing the request Origin. Auto-refresh must be enabled and a developer must visit an attacker-controlled page; the resulting EventSource exposes the filename stream but does not alter data or interrupt service.
The record
- CVE
- CVE-2026-46431
- Published
- May 26, 2026
- Updated
- May 26, 2026
- Vendor
- xyproto
- Product
- Algernon
- Classifications
- CWE-942, T1189
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 26, 2026CVE publishedPublication date reported by the CVE source.
- May 26, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 1.17.7
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Cross-origin EventSource proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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