Vulnerability in github.com/xyproto/algernon (CVE-2026-45728)
Summary
Vulnerability in github.com/xyproto/algernon (CVE-2026-45728). Confidential information can be exposed externally. Exploitable via singleFileMode. Mitigation: upgrade to 1.17.7 or later.
Original description
The description as published by the source.
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.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-45728 has been found in github.com/xyproto/algernon.
Attackers can target a specific entry point like singleFileMode over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.5/10.
What to do: upgrade github.com/xyproto/algernon to 1.17.7 or later.
If unsure, ask your IT team or search "github.com/xyproto/algernon CVE-2026-45728" on the vendor's site.
CVE-2026-45728 (github.com/xyproto/algernon) — CWE-1188 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: singleFileMode / debugMode / PrettyError / Filename
Patched: 1.17.7 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-1188) exists in github.com/xyproto/algernon. Attackers reach the vulnerable code path via singleFileMode without authentication.
Check the vendor advisory for the affected versions of github.com/xyproto/algernon. Attack surface: singleFileMode / debugMode / PrettyError / Filename.
Severity: High (CVSS 7.5/10). Confidential information can be exposed externally.
Update to 1.17.7.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/xyproto/algernon' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'github.com/xyproto/algernon' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
github.com/xyproto/algernonを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade github.com/xyproto/algernon to 1.17.7ステージング環境で 1.17.7 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- web github.com