Vulnerability in bentoml (CVE-2026-27905)
Summary
Vulnerability in bentoml (CVE-2026-27905). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 1.4.36 or later.
Original description
The description as published by the source.
Arbitrary File Write via Symlink Path Traversal in Tar Extraction
Summary
The safe_extract_tarfile() function validates that each tar member's path is within the destination directory, but for symlink members it only validates the symlink's own path, not the symlink's target. An attacker can create a malicious bento/model tar file containing a symlink pointing outside the extraction directory, followed by a regular file that writes through the symlink, achieving arbitrary file write on the host filesystem.
Affected Component
- File:
src/bentoml/_internal/utils/filesystem.py:58-96 - Callers:
src/bentoml/_internal/cloud/bento.py:542,src/bentoml/_internal/cloud/model.py:504 - Affected versions: All versions with
safe_extract_tarfile()
Severity
CVSS 3.1: 8.1 (High)
AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
Vulnerability Details
Vulnerable Code (filesystem.py:58-96)
def safe_extract_tarfile(tar, destination):
os.makedirs(destination, exist_ok=True)
for member in tar.getmembers():
fn = member.name
path = os.path.abspath(os.path.join(destination, fn))
if not Path(path).is_relative_to(destination): # Line 64: INCOMPLETE
continue # Only checks member path, NOT symlink target
if member.issym():
tar._extract_member(member, path) # Line 75: Creates symlink with UNVALIDATED target
else:
fp = tar.extractfile(member)
with open(pat…
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-2026-27905 has been found in bentoml.
Successful exploitation can lead to full system takeover. CVSS score: 7.8/10.
What to do: upgrade bentoml to 1.4.36 or later.
If unsure, ask your IT team or search "bentoml CVE-2026-27905" on the vendor's site.
CVE-2026-27905 (bentoml) — CWE-59 / CVSS v3 7.8
Attack vector: local / unauthenticated
Patched: 1.4.36 — 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-59) exists in bentoml.
Check the vendor advisory for the affected versions of bentoml.
Severity: High (CVSS 7.8/10). Successful exploitation can lead to full system takeover.
Update to 1.4.36.
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 'bentoml' . 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 'bentoml' . | 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
bentoml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 bentoml to 1.4.36ステージング環境で 1.4.36 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
- exploit security-advisories@github.com
- package github.com
- patch security-advisories@github.com