CVE-2020-25578Public exploit

Kernel-stack disclosure via uninitialized dirent offset

Published Mar 26, 2021 · Updated Aug 4, 2024

Improper initialization in FreeBSD 12.2-RELEASE before p3 allows local users to read eight bytes of kernel-stack memory. The tmpfs, smbfs, autofs, and mqueuefs VOP_READDIR implementations copy dirent structures to userspace without initializing the 64-bit d_off field. The same flaw affects 12.1-RELEASE before p13, 11.4-RELEASE before p7, 12.2-STABLE before r368969, and 11.4-STABLE before r369047; exploitation requires local access and an affected file system.

CVSS severity5.3
Medium
EPSS probability2.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper initialization in FreeBSD 12.2-RELEASE before p3 allows local users to read eight bytes of kernel-stack memory. The tmpfs, smbfs, autofs, and mqueuefs VOP_READDIR implementations copy dirent structures to userspace without initializing the 64-bit d_off field. The same flaw affects 12.1-RELEASE before p13, 11.4-RELEASE before p7, 12.2-STABLE before r368969, and 11.4-STABLE before r369047; exploitation requires local access and an affected file system.

The record

CVE
CVE-2020-25578
Published
Mar 26, 2021
Updated
Aug 4, 2024
Vendor
The FreeBSD Project
Product
FreeBSD
Classifications
CWE-665
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=FreeBSD 12.2-RELEASE before p3, 12.1-RELEASE before p13, 11.4-RELEASE before p7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The FreeBSD Project · FreeBSDversion=FreeBSD 12.2-RELEASE before p3, 12.1-RELEASE before p13, 11.4-RELEASE before p7

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N

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-665Improper Initialization

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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