CVE-2021-31859

Local privilege escalation via executable stream overwrite

Published Jul 14, 2021 · Updated Aug 3, 2024

Incorrect permissions in the MU55 FlexiSpooler service in YSoft SafeQ 6 6.0.55 allow local users to elevate privileges. The service executable permits an unprivileged user to overwrite its contents through an NTFS alternate data stream. Exploitation requires local low-privileged access and grants the service's elevated privileges when the modified executable runs.

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

Incorrect permissions in the MU55 FlexiSpooler service in YSoft SafeQ 6 6.0.55 allow local users to elevate privileges. The service executable permits an unprivileged user to overwrite its contents through an NTFS alternate data stream. Exploitation requires local low-privileged access and grants the service's elevated privileges when the modified executable runs.

The record

CVE
CVE-2021-31859
Published
Jul 14, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-732, T1574.010
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 14, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.2NIST NVDAV:L/AC:L/Au:N/C:C/I:C/A:C
7.8NIST NVDCVSS:3.1/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 exploitUnconfirmed

Weakness, pattern, technique

CWE-732Incorrect Permission Assignment for Critical Resource
T1574.010Services File Permissions Weakness

Public exploit references

No public exploit references are available in this record.

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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