CVE-2021-3571Network attack vector

Information disclosure and crash via wrong-endian follow-up length

Published Jul 9, 2021 · Updated Aug 3, 2024

Out-of-bounds read in Linux PTP Project linuxptp before 2.0.1 and 3.0 through 3.1 allows remote attackers to disclose memory or crash ptp4l. In tc_fwd_sync in tc.c, the follow-up message length is stored without conversion to network byte order, causing little-endian systems to read and transmit data beyond the message buffer. Exploitation requires network access to ptp4l operating as a transparent clock on a little-endian architecture and a crafted one-step Sync message.

CVSS severity7.1
High
EPSS probability1.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Linux PTP Project linuxptp before 2.0.1 and 3.0 through 3.1 allows remote attackers to disclose memory or crash ptp4l. In tc_fwd_sync in tc.c, the follow-up message length is stored without conversion to network byte order, causing little-endian systems to read and transmit data beyond the message buffer. Exploitation requires network access to ptp4l operating as a transparent clock on a little-endian architecture and a crafted one-step Sync message.

The record

CVE
CVE-2021-3571
Published
Jul 9, 2021
Updated
Aug 3, 2024
Vendor
Linux PTP Project
Product
linuxptp
Classifications
CWE-119, CWE-125, T1499
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Jul 9, 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=linuxptp 3.1.1, linuxptp 2.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

Linux PTP Project · linuxptpversion=linuxptp 3.1.1, linuxptp 2.0.1

Published CVSS scores

7.1Red HatCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H
5.5NIST NVDAV:N/AC:L/Au:S/C:P/I:N/A:P
7.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-125Out-of-bounds Read
T1499Endpoint Denial of Service

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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