What is the CVSS score of CVE-2020-16135?

CVE-2020-16135 has a CVSS 3.1 base score of 5.9 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 4.1%.

Is there a public PoC exploit available for CVE-2020-16135?

Yes, a public proof-of-concept exploit is available for CVE-2020-16135. Prioritise patching immediately. EPSS: 4.1%.

Is there a patch available for CVE-2020-16135?

Yes, a patch is available for CVE-2020-16135. Update the affected software to the latest version immediately.

Libssh CVE-2020-16135

MEDIUM

NULL Pointer Dereference (CWE-476)

2020-07-29 cve@mitre.org

Denial Of Service Null Pointer Dereference Debian Oracle Canonical Debian Linux Fedora Libssh Ubuntu Linux Communications Cloud Native Core Policy Fedoraproject

5.9

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-476 OWASP Top 10:2025 A10:2025 - Mishandling of Exceptional Conditions ASVS 5.0 V16 - Security Logging and Error Handling Null pointer safety, defensive checks MITRE ATT&CK 1 technique across 1 tactic: Impact The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 5.9 (MEDIUM). Attack characteristics: network attack vector, high complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available.
Exploit ScenarioDerived	A remote attacker could crash the application by dereferencing a null pointer by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

Patch available 4.1% exploitation probability (EPSS)

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AnalysisAI

libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL. Rated medium severity (CVSS 5.9), this vulnerability is remotely exploitable, no authentication required. Public exploit code available.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Check pointers before dereferencing. Use static analysis tools to detect null pointer paths.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as NULL Pointer Dereference (CWE-476), which allows attackers to crash the application by dereferencing a null pointer. libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL. Affected products include: Libssh, Debian Debian Linux, Fedoraproject Fedora, Canonical Ubuntu Linux, Oracle Communications Cloud Native Core Policy.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 5.9 MEDIUM

AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

DescriptionNVD

libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL.

Threat Intelligence Overview

EPSS Score

4.1%

Top 10% exploitable

Exploit

POC

Public exploit code exists

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity MEDIUM

CISA KEV No

Public POC Yes

EPSS 4.1%

Patch available Yes

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +4

CVSS: +30

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Null Pointer Dereference MEDIUM

A null pointer dereference occurs when a program attempts to access memory through a pointer that has been set to NULL (address 0x0).

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)NVD

cpe:2.3:a:libssh:libssh:0.9.4:*:*:*:*:*:*:*

cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*

cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*

cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*

cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*

cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*

cpe:2.3:a:oracle:communications_cloud_native_core_policy:1.15.0:*:*:*:*:*:*:*

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Same weakness CWE-476 – NULL Pointer Dereference

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References

Advisories & patches

PATCH https://www.oracle.com/security-alerts/cpuapr2022.html ADVISORY https://bugs.libssh.org/T232 REF https://gitlab.com/libssh/libssh-mirror/-/merge_requests/120 REF https://lists.debian.org/debian-lts-announce/2020/07/msg00034.html REF https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FCIKQRKXAAB4HMWM62EPZJ4DVBHIIEG6/ REF https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JNW5GBC6JFN76VEWQXMLT5F7VCZ5AJ2E/ REF https://security.gentoo.org/glsa/202011-05 REF https://usn.ubuntu.com/4447-1/

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