CVE-2021-42870Public exploitNetwork attack vector

Server crash via mishandled EPIPE write result

Published May 16, 2022 · Updated Aug 4, 2024

Out-of-bounds read in ACCEL-PPP 1.12.0 allows remote attackers to crash the PPTP server with a crafted control-packet sequence. The post_msg function treats an EPIPE write result of -1 as a byte count, then passes a pointer before the stack buffer and an enlarged length to memcpy. A network-reachable PPTP listener is required; the sequence precedes PPP authentication and terminates the process, interrupting service.

CVSS severity7.5
High
EPSS probability1.03%
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 ACCEL-PPP 1.12.0 allows remote attackers to crash the PPTP server with a crafted control-packet sequence. The post_msg function treats an EPIPE write result of -1 as a byte count, then passes a pointer before the stack buffer and an enlarged length to memcpy. A network-reachable PPTP listener is required; the sequence precedes PPP authentication and terminates the process, interrupting service.

The record

CVE
CVE-2021-42870
Published
May 16, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-125, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 16, 2022CVE 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499.004Application or System Exploitation

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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