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7 vulnerabilities by xyproto
CVE-2026-48126 (GCVE-0-2026-48126)
Vulnerability from cvelistv5 – Published: 2026-05-26 16:44 – Updated: 2026-05-26 17:27
VLAI
Title
Algernon: Host header path traversal in --domain mode reads files and runs Lua from parent dir
Summary
Algernon is a small self-contained pure-Go web server. Prior to 1.17.8, when algernon is started with --domain (or --letsencrypt, which silently turns on --domain at engine/flags.go:372), the request handler resolves the served directory by joining the configured --dir with the value of the client-supplied Host header. The join is performed by filepath.Join with no validation, so a Host: .. header walks one level above the document root. Subsequent file resolution then exposes everything in that parent directory — arbitrary file read, full directory listing, and, if any .lua file is present, server-side Lua execution. This vulnerability is fixed in 1.17.8.
Severity
8.2 (High)
CWE
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/xyproto/algernon/security/advi… | x_refsource_CONFIRM |
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CVE-2026-46431 (GCVE-0-2026-46431)
Vulnerability from cvelistv5 – Published: 2026-05-26 16:42 – Updated: 2026-05-26 17:39
VLAI
Title
Algernon: Auto-refresh SSE event server sets Access-Control-Allow-Origin: *
Summary
Algernon is a small self-contained pure-Go web server. Prior to 1.17.7, the SSE event server's Access-Control-Allow-Origin response header was hardcoded to the wildcard * regardless of the caller's Origin. Because EventSource does not preflight and does not send cookies, the wildcard is sufficient to let any third-party page the developer visits open a cross-origin EventSource to the SSE port and read the live filename stream from JavaScript. This vulnerability is fixed in 1.17.7.
Severity
4.3 (Medium)
CWE
- CWE-942 - Permissive Cross-domain Policy with Untrusted Domains
Assigner
References
1 reference
| URL | Tags |
|---|---|
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CVE-2026-46430 (GCVE-0-2026-46430)
Vulnerability from cvelistv5 – Published: 2026-05-26 16:41 – Updated: 2026-05-26 18:57
VLAI
Title
Algernon: Auto-refresh SSE event server binds to all interfaces by default on Linux/macOS
Summary
Algernon is a small self-contained pure-Go web server. Prior to 1.17.7, the SSE event server bound to 0.0.0.0:5553 on Linux/macOS by default because the platform-dependent host default in engine/flags.go:39-46 set host = "" for non-Windows, and utils.JoinHostPort("", ":5553") resolves to ":5553". This vulnerability is fixed in 1.17.7.
Severity
4.3 (Medium)
CWE
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/xyproto/algernon/security/advi… | x_refsource_CONFIRM |
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CVE-2026-45728 (GCVE-0-2026-45728)
Vulnerability from cvelistv5 – Published: 2026-05-26 16:38 – Updated: 2026-05-26 17:31
VLAI
Title
Algernon: Single-file mode unconditionally enables debug mode
Summary
Algernon is a small self-contained pure-Go web server. Prior to 1.17.7, when Algernon is invoked with a single file path instead of a directory, singleFileMode is set to true and debugMode is forcibly enabled. debugMode activates the PrettyError renderer, which on any Lua or template error response dumps the absolute path of the file that errored, complete byte contents of that file, and exception or parser error text. This response is served with HTTP 200 OK to whoever sent the request that triggered the error. Any client able to reach the server and able to provoke a runtime error in the served script obtains the full server-side source of that script and of any sibling Lua data file consulted during the request. This vulnerability is fixed in 1.17.7.
Severity
7.5 (High)
CWE
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/xyproto/algernon/security/advi… | x_refsource_CONFIRM |
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CVE-2026-45721 (GCVE-0-2026-45721)
Vulnerability from cvelistv5 – Published: 2026-05-26 16:34 – Updated: 2026-05-26 17:15
VLAI
Title
Algernon: handler.lua discovery walks parent directories above the server root
Summary
Algernon is a small self-contained pure-Go web server. Prior to 1.17.7, when Algernon is asked for any URL path that resolves to a directory without an index file, DirPage walks upward through parent directories — past the configured server root — looking for a file named handler.lua to execute as the request handler. The loop terminates only after 100 ancestor steps or when filepath.Dir returns ., so on any absolute server-root path the search reaches the filesystem root (/ on Unix, drive letter on Windows). The first handler.lua it finds is loaded into the Lua interpreter with the full Algernon API exposed — including run3(), httpclient, os.execute, io.popen, PQ, MSSQL, raw filesystem access, and the userstate database. Any process that can write handler.lua anywhere in a parent directory of the server root obtains pre-authenticated remote code execution on the next HTTP request. This is reachable without authentication — the lookup happens before the permission check returns a hit (the perm system only gates URL prefixes, not the handler-resolution step), and any URL pointing at a directory without an index triggers the walk. On a fresh stock Algernon install the request GET / is enough. This vulnerability is fixed in 1.17.7.
Severity
9 (Critical)
CWE
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/xyproto/algernon/security/advi… | x_refsource_CONFIRM |
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]
},
{
"descriptions": [
{
"cweId": "CWE-426",
"description": "CWE-426: Untrusted Search Path",
"lang": "en",
"type": "CWE"
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]
},
{
"descriptions": [
{
"cweId": "CWE-552",
"description": "CWE-552: Files or Directories Accessible to External Parties",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
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"discovery": "UNKNOWN"
},
"title": "Algernon: handler.lua discovery walks parent directories above the server root"
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CVE-2026-43981 (GCVE-0-2026-43981)
Vulnerability from cvelistv5 – Published: 2026-05-26 16:31 – Updated: 2026-05-26 16:31
VLAI
Title
Algernon: Race Condition in handle() shared LState
Summary
Algernon is a small self-contained pure-Go web server. Prior to 1.17.6, in engine/luahandler.go, the sync.RWMutex protecting LoadCommonFunctions is released before L.Push() and L.PCall() execute. Since gopher-lua's LState is explicitly not goroutine-safe, concurrent requests race on the shared state causing Lua VM corruption. The Go race detector confirms this immediately under modest concurrency (ab -n 1000 -c 100). This vulnerability is fixed in 1.17.6.
Severity
CWE
- CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/xyproto/algernon/security/advi… | x_refsource_CONFIRM |
| https://github.com/xyproto/algernon/issues/172 | x_refsource_MISC |
{
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}
],
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"userInteraction": "NONE",
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CVE-2026-43982 (GCVE-0-2026-43982)
Vulnerability from cvelistv5 – Published: 2026-05-26 16:30 – Updated: 2026-05-26 17:20
VLAI
Title
Algernon: Path traversal file write via savein()
Summary
Algernon is a small self-contained pure-Go web server. Prior to 1.17.6, uploadedFileSaveIn() in lua/upload/upload.go uses filepath.Join() with the caller-supplied directory but performs no boundary check after joining. A directory of ../../../tmp resolves cleanly to /tmp, outside the web root. This vulnerability is fixed in 1.17.6.
Severity
CWE
- CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/xyproto/algernon/security/advi… | x_refsource_CONFIRM |
| https://github.com/xyproto/algernon/issues/172 | x_refsource_MISC |
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"role": "CISA Coordinator",
"timestamp": "2026-05-26T17:17:18.510189Z",
"version": "2.0.3"
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