CVE-2020-1730Network attack vector

Client or server crash via cipher cleanup

Published Apr 13, 2020 · Updated Aug 4, 2024

NULL pointer dereference in libssh 0.8.0 through 0.8.8 and 0.9.0 through 0.9.3 allows remote attackers to crash clients or servers. The OpenSSL cipher cleanup path dereferences an uninitialized AES-CTR context when an incomplete connection closes. A malicious SSH peer can trigger the fault without authentication; a prefork server confines the crash to one session process.

CVSS severity5.3
Medium
EPSS probability3.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in libssh 0.8.0 through 0.8.8 and 0.9.0 through 0.9.3 allows remote attackers to crash clients or servers. The OpenSSL cipher cleanup path dereferences an uninitialized AES-CTR context when an incomplete connection closes. A malicious SSH peer can trigger the fault without authentication; a prefork server confines the crash to one session process.

The record

CVE
CVE-2020-1730
Published
Apr 13, 2020
Updated
Aug 4, 2024
Vendor
libssh
Product
libssh
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 13, 2020CVE 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=libssh versions before 0.8.9
  2. Affected versionversion=libssh versions before 0.9.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

libssh · libsshversion=libssh versions before 0.8.9; version=libssh versions before 0.9.4

Published CVSS scores

5.3libsshCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
5.3Red Hat, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

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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