Path Traversal in rembg (CVE-2026-40086)
Summary
Path traversal in rembg (CVE-2026-40086). Risk of unauthorized operations or information disclosure. Exploitable via model_path. Mitigation: upgrade to 2.0.75 or later.
Original description
The description as published by the source.
Summary
A path traversal vulnerability in the rembg HTTP server allows unauthenticated remote attackers to read arbitrary files from the server's filesystem. By sending a crafted request with a malicious model_path parameter, an attacker can force the server to attempt loading any file as an ONNX model, revealing file existence, permissions, and potentially file contents through error messages.
CWE IDs: CWE-22 (Path Traversal), CWE-73 (External Control of File Name or Path)
Details
Vulnerable Code Flow
The vulnerability exists in how the HTTP server handles the extras JSON parameter for custom model types (u2net_custom, dis_custom, ben_custom).
1. Entry Point - rembg/commands/s_command.py
def im_without_bg(content: bytes, commons: CommonQueryParams) -> Response:
kwargs = {}
if commons.extras:
try:
kwargs.update(json.loads(commons.extras)) # ❌ No validation
except Exception:
pass
# ...
session = new_session(commons.model, **kwargs) # Passes arbitrary kwargs
The extras parameter is parsed as JSON and passed directly to new_session() without any validation.
2. Path Handling - rembg/sessions/u2net_custom.py
@classmethod
def download_models(cls, *args, **kwargs):…
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-2026-40086 has been found in rembg.
Attackers can target a specific entry point like model_path over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade rembg to 2.0.75 or later.
If unsure, ask your IT team or search "rembg CVE-2026-40086" on the vendor's site.
CVE-2026-40086 (rembg) — CWE-22
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: model_path / extras / u2net_custom / dis_custom
Patched: 2.0.75 — 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 rembg. Attackers reach the vulnerable code path via model_path without authentication.
Check the vendor advisory for the affected versions of rembg. Attack surface: model_path / extras / u2net_custom / dis_custom.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 2.0.75.
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 'rembg' . 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 'rembg' . | 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
rembg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 rembg to 2.0.75ステージング環境で 2.0.75 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
- web github.com