CVE-2021-21813Public exploit

Local code execution via unchecked path copy

Published Aug 13, 2021 · Updated Aug 3, 2024

Stack-based buffer overflow in AT&T Labs XMill 0.7 allows local users to execute code via a crafted command-line file pattern. On Windows, HandleFileArg passes a user-controlled path prefix and its unchecked length to memcpy, which writes beyond the 400-byte fullpath stack buffer. Exploitation requires local command-line access and a file pattern containing a path separator and wildcard; the referenced file does not need to exist.

CVSS severity7.8
High
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in AT&T Labs XMill 0.7 allows local users to execute code via a crafted command-line file pattern. On Windows, HandleFileArg passes a user-controlled path prefix and its unchecked length to memcpy, which writes beyond the 400-byte fullpath stack buffer. Exploitation requires local command-line access and a file pattern containing a path separator and wildcard; the referenced file does not need to exist.

The record

CVE
CVE-2021-21813
Published
Aug 13, 2021
Updated
Aug 3, 2024
Vendor
AT&T Labs
Product
XMill
Classifications
CWE-120
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=AT&T Labs Xmill 0.7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

AT&T Labs · XMillversion=AT&T Labs Xmill 0.7

Published CVSS scores

7.8Cisco TalosCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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