LiveActive security incident?Get immediate response
CVE Record

CVE-2021-29561: CHECK-fail in `LoadAndRemapMatrix`

TensorFlow is an end-to-end open source platform for machine learning. An attacker can cause a denial of service by exploiting a `CHECK`-failure coming from `tf.raw_ops.LoadAndRemapMatrix`. This is because the implementation(https://github.com/tensorflow/tensorflow/blob/d94227d43aa125ad8b54115c03cece54f6a1977b/tensorflow/core/kernels/ragged_tensor_to_tensor_op.cc#L219-L222) assumes that the `ckpt_path` is always a valid scalar. However, an attacker can send any other tensor as the first argument of `LoadAndRemapMatrix`. This would cause the rank `CHECK` in `scalar<T>()()` to trigger and terminate the process. The fix will be included in TensorFlow 2.5.0. We will also cherrypick this commit on TensorFlow 2.4.2, TensorFlow 2.3.3, TensorFlow 2.2.3 and TensorFlow 2.1.4, as these are also affected and still in supported range.

LowCVSS 2.5Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

CVE-2021-29561 is a low-severity TensorFlow denial-of-service issue. A user who can pass an unexpected tensor into a specific raw operation can trigger an internal CHECK failure and stop the process. It does not indicate data theft or code execution.

Executive priority

Treat this as routine patching unless affected TensorFlow services process untrusted ML inputs or support multi-tenant workloads. Prioritize internet-facing or shared compute environments where process crashes could disrupt business operations.

Technical view

`tf.raw_ops.LoadAndRemapMatrix` assumed `ckpt_path` was always a valid scalar. Supplying a non-scalar tensor can trigger a rank CHECK failure in TensorFlow internals, terminating the process. Sources identify CWE-617 and patched TensorFlow releases 2.5.0, 2.4.2, 2.3.3, 2.2.3, and 2.1.4.

Likely exposure

Exposure is most likely in TensorFlow workloads running affected versions where untrusted users or jobs can influence tensors passed to raw TensorFlow operations. Typical risk is localized service or job interruption, not compromise of confidentiality or integrity.

Exploitation context

The source bundle does not show active exploitation, and KEV is false. CVSS indicates local access, high attack complexity, low privileges, no user interaction, and low availability impact. Evidence supports process termination only.

Researcher notes

The available evidence supports a denial-of-service condition from improper scalar assumptions in `LoadAndRemapMatrix`. The bundle names affected TensorFlow ranges and fixed releases. It does not support claims of remote exploitation, privilege escalation, data exposure, or weaponized use.

Mitigation direction

  • Upgrade TensorFlow to 2.5.0 or a fixed supported branch release.
  • For supported older branches, use 2.4.2, 2.3.3, 2.2.3, or 2.1.4.
  • Review the TensorFlow advisory before deploying branch-specific fixes.
  • Limit untrusted access to workflows that can invoke raw TensorFlow operations.
  • Monitor TensorFlow services for crash loops or abnormal process termination.

Validation and detection

  • Inventory TensorFlow versions across training, serving, and notebook environments.
  • Check whether affected versions are present in dependency lockfiles or containers.
  • Identify code paths using `tf.raw_ops.LoadAndRemapMatrix`.
  • Confirm deployed builds include the referenced TensorFlow fix commit or patched release.
  • Review service logs for CHECK failures or unexpected TensorFlow process exits.
Prepared
Confidence
high
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-617: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2021-29561 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Low
CVSS
2.5 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
2.5CVSS 3.1LowCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L11.4Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

2.5Low
CVSS 3.1 vector shape for CVE-2021-29561Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
tensorflowtensorflow< 2.1.4, >= 2.2.0, < 2.2.3, >= 2.3.0, < 2.3.3, >= 2.4.0, < 2.4.2Listed
Weakness

CWE details

CWE-617

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-617 · source CWE mapping

Reachable Assertion

Reachable Assertion represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs