Unsafe Deserialization in MONAI (CVE-2026-100843)
Summary
Vulnerability in MONAI (CVE-2026-100843). Successful exploitation can lead to full system takeover.
Original description
The description as published by the source.
Summary
GHSA-89gg-p5r5-q6r4 claims the pickle deserialization vulnerability in
algo_from_pickle() was fixed in v1.5.2. However, monai/auto3dseg/utils.py
has not been modified since 2024-07-12 — 18 months before v1.5.2 was released
(2026-01-29). All three pickle.loads() calls remain unchanged. The fix was
never implemented.
Vulnerable Code
File: monai/auto3dseg/utils.py (last commit: 2024-07-12, unchanged in v1.5.2)
def algo_from_pickle(pkl_filename: str, ...):
with open(pkl_filename, "rb") as f_pi:
data_bytes = f_pi.read()
data = pickle.loads(data_bytes) # SINK 1 — line 321, RCE fires here
# isinstance/key checks happen AFTER deserialization — already too late
algo_bytes = data.pop("algo_bytes")
...
if len(template_paths_candidates) == 0:
algo = pickle.loads(algo_bytes) # SINK 2 — line 350
else:
for p in template_paths_candidates:
algo = pickle.loads(algo_bytes) # SINK 3 — line 356
No Unpickler subclass, no find_class restriction, no allowlist.
Why the Fix is Incomplete
- monai/auto3dseg/utils.py last commit: 2024-07-12 ("drop python 3.8")
- v1.5.2 released: 2026-01-29 — release notes contain no pickle-related changes
- v1.5.1 and v1.5.2 contain identical code at lines 321, 350, 356
- GHSA-89gg-p5r5-q6r4 references a Zip Slip fix (unrelated) as the patch
PoC
import pickle, os
class Exploit:
def __red…
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-2026-100843 has been found in MONAI.
Successful exploitation can lead to full system takeover. CVSS score: 7.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "MONAI CVE-2026-100843" on the vendor's site.
CVE-2026-100843 (MONAI) — CWE-502 / CVSS v3 7.8
Attack vector: local / unauthenticated
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.
Unsafe deserialization (CWE-502) exists in MONAI.
Check the vendor advisory for the affected versions of MONAI.
Severity: High (CVSS 7.8/10). Successful exploitation can lead to full system takeover.
Update to the patched release per vendor advisory.
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 'MONAI' . 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 'MONAI' . | 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
MONAIを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-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 vulncheck.com
- advisory github.com
- package github.com
- web github.com
- web nvd.nist.gov
- web github.com
- web github.com