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Libssh CVE-2025-5987

| EUVDEUVD-2025-20227 HIGH
Return of Wrong Status Code (CWE-393)
2025-07-07 secalert@redhat.com
Denial Of Service OpenSSL Libssh
8.1
CVSS 3.1 · Vendor: redhat
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Vulnerability Assessment

Weakness
CWE
CWE-393
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V16 - Security Logging and Error Handling Return value error handling
Impact

Service disruption affecting availability. In critical infrastructure, DoS can have cascading effects on dependent systems. With a CVSS score of 8.1 (HIGH), this represents a significant risk.
Exploit ScenarioDerived

An attacker sends specially crafted requests that cause excessive resource consumption (CPU, memory, disk) or trigger a crash in the target application.
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 16, 2026

A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library.

Earlier versions of this analysis (1)
v1 Mar 16, 2026 - 03:37 CVSS 8.1

RemediationAI

Implement rate limiting and input validation. Use timeout mechanisms for resource-intensive operations. Deploy DDoS protection where applicable.

Affected VersionsENISA

Red Hat OpenShift Container Platform 4.20 patch: 4.20.9.6.202601211057-0
Red Hat Enterprise Linux 9.4 Extended Update Support patch: 0:0.10.4-13.el9_4.2
Red Hat Enterprise Linux 9 patch: 0:0.10.4-17.el9_7
Red Hat OpenShift Container Platform 4.19 patch: 4.19.9.6.202601260820-0
Red Hat OpenShift Container Platform 4.14 patch: 414.92.202601191325-0
Red Hat OpenShift Container Platform 4.16 patch: 416.94.202601160124-0
Red Hat OpenShift Container Platform 4.17 patch: 417.94.202601120213-0
Red Hat OpenShift Container Platform 4.15 patch: 415.92.202601271320-0
Red Hat Enterprise Linux 9.6 Extended Update Support patch: 0:0.10.4-15.el9_6.1
Red Hat OpenShift Container Platform 4.13 patch: 413.92.202602240113-0
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions patch: 0:0.10.4-9.el9_2.2
Red Hat OpenShift Container Platform 4.19 patch: 9.6.20260123-0
Red Hat Enterprise Linux 10.0 Extended Update Support patch: 0:0.11.1-4.el10_0.1
Red Hat Enterprise Linux 10 patch: 0:0.11.1-5.el10_1
Red Hat OpenShift Container Platform 4.18 patch: 418.94.202601202224-0

Affects your stack

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Technical ContextAI · show details

A denial of service vulnerability allows an attacker to disrupt the normal functioning of a system, making it unavailable to legitimate users. This vulnerability is classified as Return of Wrong Status Code (CWE-393).

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

Vendor (redhat) PRIMARY 8.1 HIGH
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Ubuntu MEDIUM
SUSE HIGH
Red Hat 8.1 MEDIUM

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
CVE Published
Jul 07, 2025 - 15:15 nvd
HIGH 8.1

DescriptionCVE.org

A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSH_OK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.

Executive ViewAI

Why It Matters

Organizations using A flaw face notable risk from CVE-2025-5987 rated CVSS 8.1. Successful exploitation could significantly impact the confidentiality, integrity, or availability of affected systems. Organizations should apply vendor updates when available and consider compensating controls in the interim.

Business Impact: High
Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.

Threat Intelligence Overview

EPSS Score
0.1%
Top 85% exploitable
Data Quality
5 sources
Confidence: Medium
EUVD NVD CVE.org EPSS Vendor

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 HIGH
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact
High

Priority Score

40
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +40
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service MEDIUM

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

More in Libssh

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CVE-2023-48795 MEDIUM POC
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The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other products, allows remot
CVE-2018-10933 CRITICAL POC
9.1 Oct 17

A vulnerability was found in libssh's server-side state machine before versions 0.7.6 and 0.8.4. Rated critical severity
CVE-2020-16135 MEDIUM POC
5.9 Jul 29

libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL. Rated medium severity (CVSS

CVE-2012-4562 HIGH
7.5 Nov 30

Multiple integer overflows in libssh before 0.5.3 allow remote attackers to cause a denial of service (infinite loop or

CVE-2012-4560 HIGH
7.5 Nov 30

Multiple buffer overflows in libssh before 0.5.3 allow remote attackers to cause a denial of service (crash) or possibly
CVE-2025-5372 HIGH
8.8 Jul 04

Cryptographic key derivation failure in libssh versions prior to 0.11.2 (when built against OpenSSL older than 3.0) can

CVE-2019-14889 HIGH
8.8 Dec 10

A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8. Rated high severi
CVE-2015-3146 HIGH
7.5 Apr 13

The (1) SSH_MSG_NEWKEYS and (2) SSH_MSG_KEXDH_REPLY packet handlers in package_cb.c in libssh before 0.6.5 do not proper
CVE-2012-6063 HIGH
7.5 Nov 30

Double free vulnerability in the sftp_mkdir function in sftp.c in libssh before 0.5.3 allows remote attackers to cause a
CVE-2012-4559 MEDIUM
6.8 Nov 30

Multiple double free vulnerabilities in the (1) agent_sign_data function in agent.c, (2) channel_request function in cha
CVE-2026-15370 HIGH
7.3 Jul 21

Stack-based buffer overflow in libssh's SFTP server allows a connected client to crash the server or potentially execute
CVE-2016-0739 MEDIUM
5.9 Apr 13

libssh before 0.7.3 improperly truncates ephemeral secrets generated for the (1) diffie-hellman-group1 and (2) diffie-he

Same weakness CWE-393 – Return of Wrong Status Code

View all
CVE-2024-49117 HIGH
8.8
CVE-2026-53092 HIGH
7.8
CVE-2026-92821 MEDIUM
6.8
CVE-2025-24531 MEDIUM
6.7
CVE-2020-5401 MEDIUM
5.3
CVE-2025-32414 MEDIUM POC
5.6

Same technique Denial Of Service

View all
CVE-2015-5119 CRITICAL POC
9.8
CVE-2011-2462 CRITICAL POC
9.8
CVE-2011-0611 HIGH POC
8.8
CVE-2012-1889 HIGH POC
8.8
CVE-2012-0507 CRITICAL POC
9.8
CVE-2014-1761 HIGH POC
7.8
CVE-2015-5122 CRITICAL POC
9.8
CVE-2011-0609 HIGH POC
7.8

Vendor StatusVendor

Ubuntu

Priority: Medium
libssh
Release Status Version
noble released 0.10.6-2ubuntu0.1
oracular released 0.10.6-3ubuntu1.1
plucky released 0.11.1-1ubuntu0.1
upstream released 0.11.2
bionic not-affected code not present
focal not-affected code not present
jammy not-affected code not present
xenial not-affected code not present
USN-7619-1

Debian

Bug #1108407
libssh
Release Status Fixed Version Urgency
bullseye not-affected - -
bullseye (security) fixed 0.9.8-0+deb11u2 -
bookworm fixed 0.10.6-0+deb12u2 -
bookworm (security) vulnerable 0.10.6-0+deb12u1 -
trixie fixed 0.11.2-1+deb13u1 -
forky fixed 0.11.3-1 -
sid fixed 0.12.0-1 -
(unstable) fixed 0.11.2-1 -

SUSE

Severity: High
Product Status
Container suse/sl-micro/6.1/baremetal-os-container:2.2.1-7.2 Container suse/sl-micro/6.1/base-os-container:2.2.1-5.27 Container suse/sl-micro/6.1/kvm-os-container:2.2.1-5.29 Container suse/sl-micro/6.1/rt-os-container:2.2.1-5.14 Image SL-Micro Image SL-Micro-Azure Image SL-Micro-BYOS-Azure Image SL-Micro-BYOS-EC2 Image SL-Micro-BYOS-GCE Image SL-Micro-Base Image SL-Micro-Base-RT Image SL-Micro-Base-RT-SelfInstall Image SL-Micro-Base-RT-encrypted Image SL-Micro-Base-SelfInstall Image SL-Micro-Base-encrypted Image SL-Micro-Base-qcow Image SL-Micro-Default Image SL-Micro-Default-SelfInstall Image SL-Micro-Default-encrypted Image SL-Micro-Default-qcow Image SL-Micro-EC2 Image SLE-Micro Image SLE-Micro-Azure Image SLE-Micro-BYOS Image SLE-Micro-BYOS-Azure Image SLE-Micro-BYOS-EC2 Image SLE-Micro-BYOS-GCE Image SLE-Micro-EC2 Image SLE-Micro-GCE Image SUSE-Multi-Linux-Manager-Proxy-BYOS-Azure Image SUSE-Multi-Linux-Manager-Proxy-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Proxy-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-Azure-llc Image SUSE-Multi-Linux-Manager-Server-Azure-ltd Image SUSE-Multi-Linux-Manager-Server-BYOS-Azure Image SUSE-Multi-Linux-Manager-Server-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Server-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-EC2-llc Image SUSE-Multi-Linux-Manager-Server-EC2-ltd Affected
SUSE Liberty Linux 9 Fixed
SUSE Linux Enterprise Server 16.0 Fixed
SUSE Linux Micro 6.0 Fixed
SUSE Linux Micro 6.1 Fixed

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2025-5987 ADVISORY https://ubuntu.com/security/notices/USN-7619-1 ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:20557/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2025:20596/ REF https://access.redhat.com/errata/RHSA-2025:23483 REF https://access.redhat.com/errata/RHSA-2025:23484 REF https://access.redhat.com/errata/RHSA-2026:0427 REF https://access.redhat.com/errata/RHSA-2026:0428 REF https://access.redhat.com/errata/RHSA-2026:0430 REF https://access.redhat.com/errata/RHSA-2026:0431 REF https://access.redhat.com/errata/RHSA-2026:0702 REF https://access.redhat.com/errata/RHSA-2026:0978 REF https://access.redhat.com/errata/RHSA-2026:0980 REF https://access.redhat.com/errata/RHSA-2026:0985 REF https://access.redhat.com/errata/RHSA-2026:0996 REF https://access.redhat.com/errata/RHSA-2026:1539 REF https://access.redhat.com/errata/RHSA-2026:1541 REF https://access.redhat.com/errata/RHSA-2026:3415 REF https://access.redhat.com/security/cve/CVE-2025-5987 REF https://bugzilla.redhat.com/show_bug.cgi?id=2376219 REF https://www.libssh.org/security/advisories/CVE-2025-5987.txt

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