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NVD / CVE Program· CNA GitHub_M

CVE-2021-37686: Infinite loop in TensorFlow Lite

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.17% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: tensorflow (PyPI) 2.3.4, 2.4.3, 2.6.0rc2; tensorflow-cpu (PyPI) 2.3.4, 2.4.3, 2.6.0rc2; tensorflow-gpu (PyPI) 2.3.4, 2.4.3, 2.6.0rc2.

Low priority for now. Upgrade to tensorflow (PyPI) 2.3.4, 2.4.3, 2.6.0rc2; tensorflow-cpu (PyPI) 2.3.4, 2.4.3, 2.6.0rc2; tensorflow-gpu (PyPI) 2.3.4, 2.4.3, 2.6.0rc2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

TensorFlow is an end-to-end open source platform for machine learning. In affected versions the strided slice implementation in TFLite has a logic bug which can allow an attacker to trigger an infinite loop. This arises from newly introduced support for [ellipsis in axis definition](https://github.com/tensorflow/tensorflow/blob/149562d49faa709ea80df1d99fc41d005b81082a/tensorflow/lite/kernels/strided_slice.cc#L103-L122). An attacker can craft a model such that `ellipsis_end_idx` is smaller than `i` (e.g., always negative). In this case, the inner loop does not increase `i` and the `continue` statement causes execution to skip over the preincrement at the end of the outer loop. We have patched the issue in GitHub commit dfa22b348b70bb89d6d6ec0ff53973bacb4f4695. TensorFlow 2.6.0 is the only affected version.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Aug 12, 2021
Updated
Jun 17, 2026
EPSS
0.1% · 6th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CNA vs NVD score

NVD
5.5
CNA · GitHub_M
5.5
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
googletensorflow

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • google tensorflow2.3.0 and later · before 2.3.4
  • google tensorflow2.4.0 and later · before 2.4.3
  • google tensorflow2.5.0
  • google tensorflow2.6.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • tensorflow tensorflow

    • >= 2.6.0rc0, < 2.6.0rc2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
PyPItensorflowfrom 2.3.0 · before 2.3.42.3.4
PyPItensorflowfrom 2.4.0 · before 2.4.32.4.3
PyPItensorflowfrom 2.6.0rc0 · before 2.6.0rc22.6.0rc2
PyPItensorflow-cpufrom 2.3.0 · before 2.3.42.3.4
PyPItensorflow-cpufrom 2.4.0 · before 2.4.32.4.3
PyPItensorflow-cpufrom 2.6.0rc0 · before 2.6.0rc22.6.0rc2
PyPItensorflow-gpufrom 2.3.0 · before 2.3.42.3.4
PyPItensorflow-gpufrom 2.4.0 · before 2.4.32.4.3
PyPItensorflow-gpufrom 2.6.0rc0 · before 2.6.0rc22.6.0rc2

Same product

google: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-25668TensorFlow vulnerable to heap out-of-buffer read in the QuantizeAndDequantize operation
    39Monitor
  • CVE-2023-25664TensorFlow vulnerable to Heap Buffer Overflow in AvgPoolGrad
    39Monitor
  • CVE-2022-41900FractionalMaxPool and FractionalAVGPool heap out-of-bounds acess in Tensorflow
    39Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2021-37680Aug 12, 2021 · Division by zero in TFLite in TensorFlow
    22Monitor
  • ← EarlierCVE-2021-37681Aug 12, 2021 · Null pointer exception in TensorFlow Lite
    31Monitor
  • Later →CVE-2021-37688Aug 12, 2021 · Null pointer dereference in TensorFlow Lite
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
PyPI:tensorflow2.3.4Package registry (OSV)
PyPI:tensorflow2.4.3Package registry (OSV)
PyPI:tensorflow2.6.0rc2Package registry (OSV)
PyPI:tensorflow-cpu2.3.4Package registry (OSV)
PyPI:tensorflow-cpu2.4.3Package registry (OSV)
PyPI:tensorflow-cpu2.6.0rc2Package registry (OSV)
PyPI:tensorflow-gpu2.3.4Package registry (OSV)
PyPI:tensorflow-gpu2.4.3Package registry (OSV)
PyPI:tensorflow-gpu2.6.0rc2Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-835 · Loop with Unreachable Exit Condition ('Infinite Loop')

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records