Vulnerability in github.com/xyproto/algernon (CVE-2026-46431)
Summary
Vulnerability in github.com/xyproto/algernon (CVE-2026-46431). Risk of unauthorized operations or information disclosure. Exploitable via Origin. 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, 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.
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-2026-46431 has been found in github.com/xyproto/algernon.
Attackers can target a specific entry point like Origin over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.3/10.
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-2026-46431" on the vendor's site.
CVE-2026-46431 (github.com/xyproto/algernon) — CWE-942 / CVSS v3 4.3
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: Origin / EventSource / recwatch / GET
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-942) exists in github.com/xyproto/algernon. Attackers reach the vulnerable code path via Origin without authentication.
Check the vendor advisory for the affected versions of github.com/xyproto/algernon. Attack surface: Origin / EventSource / recwatch / GET.
Severity: Medium (CVSS 4.3/10). Risk of unauthorized operations or information disclosure.
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
-
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 nvd.nist.gov
- advisory github.com
- package github.com
- web github.com