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CVE Record

CVE-2021-21815: A stack-based buffer overflow vulnerability exists in the command-line-parsing HandleFileArg functionality...

A stack-based buffer overflow vulnerability exists in the command-line-parsing HandleFileArg functionality of AT&T Labs' Xmill 0.7. Within the function HandleFileArg the argument filepattern is under control of the user who passes it in from the command line. filepattern is passed directly to strcpy copying the path provided by the user into a staticly sized buffer without any length checks resulting in a stack-buffer overflow. An attacker can provide malicious input to trigger this vulnerability.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2021-21815 affects AT&T Labs Xmill 0.7, a legacy command-line tool. A local user can supply an overly long file pattern that overflows a stack buffer. Successful exploitation could let an attacker crash the process or potentially run code with the privileges of the Xmill process.

Executive priority

Treat this as high priority where Xmill 0.7 exists in production, shared servers, or automated ingestion paths. The vulnerability is local, but impact could be severe if the process has meaningful privileges.

Technical view

The flaw is in Xmill 0.7 HandleFileArg command-line parsing. User-controlled filepattern input is copied with strcpy into a statically sized stack buffer without length checks, causing a stack-based buffer overflow. CVSS 3.0 is 7.8: local attack vector, low complexity, low privileges required, no user interaction, and high confidentiality, integrity, and availability impact.

Likely exposure

Exposure is most likely in environments that still run AT&T Labs Xmill 0.7 directly or through legacy data processing scripts. Risk increases if local users or automated workflows can influence file patterns passed to Xmill.

Exploitation context

The provided sources describe malicious local input as the trigger. The CVE is not listed as KEV in the bundle, and no supplied source states active exploitation in the wild.

Researcher notes

Evidence is strongest for root cause, affected version, and CVSS impact. The bundle does not name a fixed version, patch, or active exploitation. Focus validation on finding Xmill 0.7 usage and argument-control paths.

Mitigation direction

  • Inventory systems and build images for AT&T Labs Xmill 0.7.
  • Remove or disable Xmill where it is no longer required.
  • Restrict local users and automation paths that can invoke Xmill.
  • Check AT&T Labs or Talos guidance for any fixed release or vendor mitigation.
  • Run legacy processing jobs with least privilege and isolation.

Validation and detection

  • Confirm installed Xmill versions and provenance on relevant hosts.
  • Review scripts and scheduled jobs that pass file patterns to Xmill.
  • Identify whether untrusted users can influence Xmill command-line arguments.
  • Verify compensating controls restrict execution and limit process privileges.
Prepared
Confidence
medium
Sources
3

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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CVE-2021-21815 mapping review

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

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.0)
Known Exploited
No
Published

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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
2Source 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
7.8CVSS 3.0HighCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Primary CVE score

Vulnerability scoring details

Base CVSS 3.0 score

7.8High
CVSS 3.0 vector shape for CVE-2021-21815Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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
n/aAT&TAT&T Labs Xmill 0.7Listed
Weakness

CWE details

No CWE listed

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