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CVE Record

CVE-2021-21812: 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 static sized buffer without any length checks resulting in a stack-buffer overflow. An attacker can provide malicious input to trigger these vulnerabilities.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

AT&T Labs Xmill 0.7 has a local command-line parsing flaw. A user who can run Xmill with a crafted file pattern may trigger memory corruption, with rated impacts to confidentiality, integrity, and availability. This is not a remote internet-facing issue by default, but it matters where Xmill processes untrusted inputs or runs in automated workflows.

Executive priority

Prioritize remediation where Xmill is used in production, batch processing, or shared environments. Business urgency is lower than internet-facing RCE, but high impact ratings justify removal, replacement, or strict containment if Xmill remains in use.

Technical view

The reported flaw is a stack-based buffer overflow in HandleFileArg. The user-controlled filepattern argument is copied with strcpy into a fixed-size stack buffer without length checks. CVSS 3.0 is 7.8: local attack vector, low complexity, low privileges, no user interaction, and high CIA impact.

Likely exposure

Exposure is likely limited to systems where AT&T Labs Xmill 0.7 is installed and executable by users or automation. Risk increases if jobs pass externally supplied filenames, paths, or patterns into Xmill.

Exploitation context

Sources describe malicious command-line input as the trigger. The CVE is not listed as KEV in the bundle, and the provided sources do not claim active exploitation. Treat exploit status as unconfirmed.

Researcher notes

The core evidence is the unsafe strcpy use in HandleFileArg with filepattern under user control. CVSS indicates local exploitation with low privileges. The source bundle provides no CWE mapping, no confirmed patch, and no active exploitation evidence.

Mitigation direction

  • Inventory systems for AT&T Labs Xmill 0.7 installations.
  • Avoid passing untrusted file patterns or paths into Xmill.
  • Restrict execution to trusted users and controlled automation.
  • Isolate Xmill processing from sensitive data and privileged contexts.
  • Check vendor or Talos guidance; no patch is named in the source bundle.

Validation and detection

  • Confirm whether Xmill 0.7 exists on endpoints, servers, containers, or build images.
  • Review scheduled jobs and scripts that invoke Xmill.
  • Check whether any Xmill inputs originate from users, uploads, or external feeds.
  • Verify execution permissions and service account privileges around Xmill workflows.
  • Document compensating controls if no vendor fix is available.
Prepared
Confidence
high
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-2021-21812 mapping review

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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-2021-21812Attack 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.