CVE-2022-41908: TensorFlow: DoS via invalid UTF-8 input to PyFunc op

HIGH PoC AVAILABLE CISA: TRACK*
Published November 18, 2022
CISO Take

Any TensorFlow serving infrastructure exposing models that accept string inputs via PyFunc is vulnerable to a trivial, unauthenticated crash. An attacker sending a single malformed UTF-8 byte sequence takes down the serving process — no authentication, no complexity. Patch to TF 2.11, 2.10.1, 2.9.3, or 2.8.4 immediately; add UTF-8 input validation at the API gateway as a defense-in-depth layer.

Risk Assessment

High (CVSS 7.5). Network-reachable with no privileges or user interaction required makes this trivially weaponizable against public-facing model serving endpoints. The blast radius is limited to availability — no data exfiltration or code execution — but a single malformed request can crash the TF process. Risk is elevated in multi-tenant inference platforms where a single tenant crash could cascade to shared infrastructure.

Affected Systems

Package Ecosystem Vulnerable Range Patched
tensorflow pip No patch
195.0K OpenSSF 7.2 3.7K dependents Pushed today 4% patched ~1372d to patch Full package profile →

Do you use tensorflow? You're affected.

Severity & Risk

CVSS 3.1
7.5 / 10
EPSS
0.3%
chance of exploitation in 30 days
Higher than 53% of all CVEs
Exploitation Status
Exploit Available
Exploitation: MEDIUM
Sophistication
Trivial
Exploitation Confidence
medium
CISA SSVC: Public PoC
Public PoC indexed (trickest/cve)
Composite signal derived from CISA KEV, CISA SSVC, EPSS, trickest/cve, and Nuclei templates.

Attack Surface

AV AC PR UI S C I A
AV Network
AC Low
PR None
UI None
S Unchanged
C None
I None
A High

Recommended Action

5 steps
  1. Patch: Upgrade to TensorFlow 2.11, 2.10.1, 2.9.3, or 2.8.4.

  2. Workaround: Validate all string inputs are valid UTF-8 before invoking PyFunc — use Python's str.encode('utf-8') with error handling or a gateway-level sanitizer.

  3. API gateway: Add input schema validation rejecting invalid byte sequences before they reach the TF runtime.

  4. Detection: Monitor for sudden TF process restarts/crashes correlated with unusual input patterns in serving logs.

  5. Container isolation: Ensure TF serving runs in isolated containers so a crash does not affect other services.

CISA SSVC Assessment

Decision Track*
Exploitation poc
Automatable No
Technical Impact partial

Source: CISA Vulnrichment (SSVC v2.0). Decision based on the CISA Coordinator decision tree.

Classification

Compliance Impact

This CVE is relevant to:

EU AI Act
Article 15 - Accuracy, Robustness and Cybersecurity
ISO 42001
8.4 - AI System Operation and Monitoring
NIST AI RMF
MANAGE-2.4 - Residual risks and errors are monitored and managed
OWASP LLM Top 10
LLM04 - Model Denial of Service

Frequently Asked Questions

What is CVE-2022-41908?

Any TensorFlow serving infrastructure exposing models that accept string inputs via PyFunc is vulnerable to a trivial, unauthenticated crash. An attacker sending a single malformed UTF-8 byte sequence takes down the serving process — no authentication, no complexity. Patch to TF 2.11, 2.10.1, 2.9.3, or 2.8.4 immediately; add UTF-8 input validation at the API gateway as a defense-in-depth layer.

Is CVE-2022-41908 actively exploited?

Proof-of-concept exploit code is publicly available for CVE-2022-41908, increasing the risk of exploitation.

How to fix CVE-2022-41908?

1. Patch: Upgrade to TensorFlow 2.11, 2.10.1, 2.9.3, or 2.8.4. 2. Workaround: Validate all string inputs are valid UTF-8 before invoking PyFunc — use Python's str.encode('utf-8') with error handling or a gateway-level sanitizer. 3. API gateway: Add input schema validation rejecting invalid byte sequences before they reach the TF runtime. 4. Detection: Monitor for sudden TF process restarts/crashes correlated with unusual input patterns in serving logs. 5. Container isolation: Ensure TF serving runs in isolated containers so a crash does not affect other services.

What systems are affected by CVE-2022-41908?

This vulnerability affects the following AI/ML architecture patterns: model serving, training pipelines, inference APIs.

What is the CVSS score for CVE-2022-41908?

CVE-2022-41908 has a CVSS v3.1 base score of 7.5 (HIGH). The EPSS exploitation probability is 0.30%.

Technical Details

NVD Description

TensorFlow is an open source platform for machine learning. An input `token` that is not a UTF-8 bytestring will trigger a `CHECK` fail in `tf.raw_ops.PyFunc`. We have patched the issue in GitHub commit 9f03a9d3bafe902c1e6beb105b2f24172f238645. The fix will be included in TensorFlow 2.11. We will also cherrypick this commit on TensorFlow 2.10.1, 2.9.3, and TensorFlow 2.8.4, as these are also affected and still in supported range.

Exploitation Scenario

An adversary identifies an internet-facing model inference API backed by TensorFlow. They send a POST request with a token field containing a byte sequence that is not valid UTF-8 (e.g., a raw 0xFF byte). TensorFlow's PyFunc performs a CHECK assertion on the token's encoding — the assertion fails, triggering an immediate process abort via SIGABRT. The serving container crashes, returning 503 to legitimate users. An attacker can automate this in a loop to maintain a sustained denial-of-service against the inference endpoint with minimal resources, no credentials, and without triggering typical rate-limit defenses since each request is a single packet.

Weaknesses (CWE)

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Timeline

Published
November 18, 2022
Last Modified
November 21, 2024
First Seen
November 18, 2022

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