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CVE Record

CVE-2021-35331: In Tcl 8.6.11, a format string vulnerability in nmakehlp.c might allow code execution via a crafted file.

In Tcl 8.6.11, a format string vulnerability in nmakehlp.c might allow code execution via a crafted file. NOTE: multiple third parties dispute the significance of this finding

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-35331 reports a possible code-execution issue in Tcl 8.6.11 involving a format string flaw in nmakehlp.c and a crafted file. The record also says multiple third parties dispute the significance, and the source bundle provides no CVSS score or confirmed affected-product metadata.

Executive priority

Low-to-monitoring priority unless Tcl 8.6.11 is confirmed in business-critical build or operational paths. There is no KEV evidence, no CVSS score, and the CVE record itself notes disputed significance.

Technical view

The CVE describes a format string vulnerability in Tcl 8.6.11's nmakehlp.c that might allow code execution through crafted input. Public metadata is sparse: no CWE, no CVSS vector, no complete CPE list, and disputed impact. Treat this as a source-level finding requiring environment-specific validation.

Likely exposure

Exposure is only supported where Tcl 8.6.11 or related source/build components including nmakehlp.c are present. The bundle does not identify downstream products, packaged builds, operating systems, or runtime exposure paths.

Exploitation context

The CVE is not listed as KEV in the provided bundle, and no cited source here confirms active exploitation. The record itself notes disputed significance, so exploitation likelihood and practical impact remain unclear from these sources.

Researcher notes

Focus on confirming the exact Tcl source version, whether nmakehlp.c is present, and whether any trusted workflow processes attacker-controlled files. Do not assume downstream impact without product-specific evidence.

Mitigation direction

  • Inventory Tcl 8.6.11 source or packaged use in your environment.
  • Review linked Tcl upstream changes and vendor advisories for applicable fixes.
  • Prioritize remediation only after confirming the vulnerable component is reachable.
  • Avoid processing untrusted crafted files with affected Tcl build components.
  • Track vendor package updates rather than applying unverified local assumptions.

Validation and detection

  • Check asset inventories for Tcl 8.6.11 references.
  • Confirm whether nmakehlp.c exists in deployed or build environments.
  • Review build pipelines for Tcl source handling and untrusted file inputs.
  • Compare local Tcl source against the linked upstream commits.
  • Document uncertainty if no reachable exposure path is found.
Prepared
Confidence
medium
Sources
6

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

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description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2021-35331 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
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.

0CVSS vectors
0Timeline events
0ADP providers
5Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

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