LiveActive security incident?Get immediate response
CVE Record

CVE-2021-29617: Crash in `tf.strings.substr` due to `CHECK`-fail

TensorFlow is an end-to-end open source platform for machine learning. An attacker can cause a denial of service via `CHECK`-fail in `tf.strings.substr` with invalid arguments. 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
Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

CVE-2021-29617 is a low-severity TensorFlow denial-of-service issue. Invalid arguments to `tf.strings.substr` can trigger an internal CHECK failure and crash the process. It does not indicate data theft or code execution, but it can interrupt workloads that expose this function path to untrusted or low-privileged users.

Executive priority

Treat this as a routine patching item unless affected TensorFlow workloads are multi-tenant, user-facing, or business-critical. The business risk is service interruption, not data exposure or system takeover based on the provided evidence.

Technical view

The issue is classified as CWE-755 and affects TensorFlow versions before patched maintenance releases across 2.1, 2.2, 2.3, and 2.4. The CVSS 3.1 vector is local, high complexity, low privileges, no user interaction, unchanged scope, and low availability impact only.

Likely exposure

Exposure is most likely in ML applications, notebooks, batch jobs, or services using affected TensorFlow versions where a user can influence arguments passed to `tf.strings.substr`. Systems not using TensorFlow string substring operations have lower practical exposure.

Exploitation context

The provided sources do not show active exploitation, and the CVE is not listed as KEV. The issue requires local access or a local-equivalent application path with low privileges and invalid function arguments, resulting in process denial of service rather than compromise.

Researcher notes

The primary evidence is the TensorFlow advisory and linked fix commit. The vulnerability is a CHECK-fail denial of service caused by invalid arguments. Sources do not provide evidence of remote exploitation, weaponization, or impacts beyond availability.

Mitigation direction

  • Upgrade TensorFlow to 2.5.0 or a patched maintenance release for your supported branch.
  • Use TensorFlow 2.4.2, 2.3.3, 2.2.3, or 2.1.4 where staying on those branches.
  • Inventory containers, notebooks, CI images, and production ML runtimes for affected TensorFlow versions.
  • Review vendor advisory guidance if an immediate upgrade is not possible.
  • Restrict untrusted control over TensorFlow substring arguments until patched.

Validation and detection

  • Check deployed TensorFlow versions against the affected version ranges in the advisory.
  • Identify code paths that call `tf.strings.substr` with user-controlled inputs.
  • Confirm upgraded environments use the patched branch versions or TensorFlow 2.5.0 or later.
  • Review crash logs for TensorFlow CHECK failures involving string substring operations.
Prepared
Confidence
high
Sources
6

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-755: 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-2021-29617 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
5Source 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-2021-29617Attack 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
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 links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-755 · source CWE mapping

Improper Handling of Exceptional Conditions

Improper Handling of Exceptional Conditions represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.