Authentication Bypass in github.com/rclone/rclone (CVE-2026-88018)
Summary
Authentication bypass in github.com/rclone/rclone (CVE-2026-88018). Successful exploitation can lead to full system takeover. Exploitable via authPairMiddleware. Mitigation: upgrade to 1.75.1 or later.
Original description
The description as published by the source.
rclone is a command-line program to sync files and directories to and from different cloud storage providers. Prior to 1.75.1, rclone serve s3 configured with --auth-proxy but without --auth-key allows authPairMiddleware to register any client-chosen accessKeyID with an empty ws.s3Secret. gofakes3 then verifies the request’s SigV4 signature against that same empty secret, while Server.auth passes the access key identifier as both the user and authentication value to the proxy without an independent per-identity secret. An unauthenticated network attacker can therefore choose an arbitrary access key, sign with an empty secret, and reach whatever backend the auth-proxy script resolves for that identity. This issue is fixed in version 1.75.1.
Source: NIST National Vulnerability Database 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-2026-88018 has been found in github.com/rclone/rclone.
Attackers can target a specific entry point like authPairMiddleware over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: upgrade github.com/rclone/rclone to 1.75.1 or later.
If unsure, ask your IT team or search "github.com/rclone/rclone CVE-2026-88018" on the vendor's site.
CVE-2026-88018 (github.com/rclone/rclone) — CWE-287 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: authPairMiddleware / proxyAuthMiddleware / Authorization / AddAuthKeys
Patched: 1.75.1 — 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.
Authentication bypass (CWE-287) exists in github.com/rclone/rclone. Attackers reach the vulnerable code path via authPairMiddleware without authentication.
Check the vendor advisory for the affected versions of github.com/rclone/rclone. Attack surface: authPairMiddleware / proxyAuthMiddleware / Authorization / AddAuthKeys.
Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.
Update to 1.75.1.
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/rclone/rclone' . 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/rclone/rclone' . | 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/rclone/rclone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/rclone/rclone to 1.75.1ステージング環境で 1.75.1 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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-88018 rclone
References
- advisory github.com
- patch github.com
- web github.com
- web nvd.nist.gov
- web github.com