{"id":"CVE-2026-32771","aliases":["GHSA-f7cq-gvh6-qr25","GO-2026-4712"],"url":"https://o3.security/vulnerability/CVE-2026-32771","summary":"Monitoring is vulnerable to Archive Slip due to missing checks in sanitization","details":"The `sanitizeArchivePath` function in `pkg/extract/extract.go` (lines 248–254) is vulnerable to a path traversal bypass due to a missing trailing path separator in the `strings.HasPrefix` check. A crafted tar archive can write files outside the intended destination directory when using the `extractor` CLI tool or the `extract.DumpOTelCollector` library function.\n\n## Vulnerable Code\n\nFile: `pkg/extract/extract.go`, lines 248–254\n\n```go\nfunc sanitizeArchivePath(d, t string) (v string, err error) {\n    v = filepath.Join(d, t)\n    if strings.HasPrefix(v, filepath.Clean(d)) {   // ← missing trailing separator\n        return v, nil\n    }\n    return \"\", fmt.Errorf(\"filepath is tainted: %s\", t)\n}\n```\n\nThe function is called at line 219 inside `untar`, which is invoked by `copyFromPod` (line 205) during the Cold Extract data dump workflow.\n\n## Root Cause\n\n`strings.HasPrefix(v, filepath.Clean(d))` does not append a trailing `/` to the directory prefix, causing a **directory name prefix collision**. If the destination is `/home/user/extract-output` and a tar entry is named `../extract-outputevil/pwned`, the joined path `/home/user/extract-outputevil/pwned` passes the prefix check — it starts with `/home/user/extract-output` — even though it is entirely outside the intended directory.\n\n## Steps to Reproduce\n\n1. **Deploy the monitoring stack** with `ColdExtract: true`. The OTEL Collector begins writing signal data (`otel_traces`, `otel_metrics`, `otel_logs`) to the shared PVC.\n\n2. **Place the PoC tar on the PVC.** Any pod with write access to the `ReadWriteMany` PVC (or the compromised OTEL Collector itself) copies a `poc-path-traversal.tar` into the `/data/collector` mount path. The archive contains three real-looking OTLP telemetry files alongside two crafted entries with path-traversal names.\n\n3. **Run the extractor against the namespace:**\n\n   ```\n   extractor \\\n     --namespace monitoring \\\n     --pvc-name <signals-pvc-name> \\\n     --directory /home/user/extract-output\n   ```\n\n4. **Observe the bypass.** `untar` processes the tar stream. For the malicious entries:\n\n   ```\n   // entry name: ../extract-outputevil/poc-proof.txt\n   filepath.Join(\"/home/user/extract-output\", \"../extract-outputevil/poc-proof.txt\")\n     => \"/home/user/extract-outputevil/poc-proof.txt\"\n\n   strings.HasPrefix(\"/home/user/extract-outputevil/poc-proof.txt\",\n                     \"/home/user/extract-output\")\n     => true   // BUG: prefix collision; file lands OUTSIDE target dir\n   ```\n\n   Both malicious entries are written outside `/home/user/extract-output/`. The three legitimate OTLP files land correctly inside it.\n\n## Impact\n\nSuccessful exploitation gives an attacker arbitrary file write on the machine running the extractor. Real-world primitives include:\n\n- Overwriting `~/.bashrc` / `~/.zshrc` / `~/.profile` for RCE on next shell login\n- Appending to `~/.ssh/authorized_keys` for persistent SSH backdoor\n- Dropping a malicious entry into `~/.kube/config` to hijack cluster access\n- Writing crontab entries for persistent scheduled execution\n\nThe attack surface is widened by the default `ReadWriteMany` PVC access mode, which means any pod in the cluster with the PVC mounted can inject the payload — not just the OTEL Collector itself.","published":"2026-03-20T00:29:23.804Z","modified":"2026-09-13T03:45:53.263698295Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/ctfer-io/monitoring","fixedVersion":"0.2.2"}],"fix":{"url":"https://github.com/ctfer-io/monitoring/commit/269dba165aa42210352628c0db6756f3b8fd3c8a","label":"ctfer-io/monitoring@269dba1"},"references":[{"type":"WEB","url":"https://security.snyk.io/research/zip-slip-vulnerability#expandable-socPI9fFAJ-title"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/32xxx/CVE-2026-32771.json"},{"type":"ADVISORY","url":"https://github.com/ctfer-io/monitoring/security/advisories/GHSA-f7cq-gvh6-qr25"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-32771"},{"type":"FIX","url":"https://github.com/ctfer-io/monitoring/commit/269dba165aa42210352628c0db6756f3b8fd3c8a"},{"type":"PACKAGE","url":"https://github.com/ctfer-io/monitoring"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-13T03:45:53.263698295Z"}}