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Red Hat Enterprise Linux 10 EUVDEUVD-2026-16332

| CVE-2026-0967 MEDIUM
Inefficient Regular Expression Complexity (ReDoS) (CWE-1333)
2026-03-26 redhat GHSA-6jpg-fr24-wpvf
Denial Of Service Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 9 Red Hat Openshift Container Platform 4 Red Hat
5.5
CVSS 3.1 · NVD
Temporal: 2.2
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Vulnerability Assessment

Weakness
CWE
CWE-1333
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V2 - Validation and Business Logic Regex complexity limits
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.

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Impact

The CVSS 3.0 vector (AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L) indicates a local-only attack requiring limited privileges, high complexity, and user interaction to trigger, with impact limited to availability (low severity). The CVSS score of 2.2 correctly reflects this as a low-severity finding. However, real-world risk depends on several factors: (1) Attack Vector Local (AV:L) means only local users or those with filesystem access can exploit it; (2) Access Complexity High (AC:H) suggests the attacker must satisfy specific conditions (e.g., timing or specific system state) to trigger the DoS; (3) User Interaction Required (UI:R) means the victim must interact with the malicious configuration (e.g., open a new SSH session). The vulnerability is not actively exploited per CISA KEV lists, and no public exploit code has been reported in the provided intelligence. EPSS score is not provided, but the combination of local-only attack surface, high complexity, and required user interaction suggests low exploitability in practice. Remediation priority should be moderate-address during regular patching cycles rather than emergency patching, unless the organization runs SSH clients in high-availability environments where even brief DoS events create business impact.
Exploit ScenarioDerived

An attacker with local system access (e.g., a non-root user on a shared system) crafts a malicious entry in the shared or user-specific known_hosts file or .ssh/config with a hostname pattern such as '(a+)+b' or similar polynomial/exponential backtracking pattern. When the SSH client is invoked by the victim (with user interaction) and calls match_pattern() to validate the hostname against this crafted pattern, the regex engine enters pathological backtracking, consuming CPU and memory until the operation times out or the system becomes unresponsive. The victim's SSH session fails, creating a denial of service. No public proof-of-concept code is documented in the provided intelligence, and this is not a confirmed active exploitation scenario (no KEV status), suggesting it remains a theoretical but plausible attack in environments with strict access controls or in containerized platforms where multiple tenants share node resources.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 26, 2026

libssh's match_pattern() function is vulnerable to ReDoS (Regular Expression Denial of Service) attacks when processing maliciously crafted hostnames in client configuration or known_hosts files, allowing local attackers with limited privileges and user interaction to trigger inefficient regex backtracking that exhausts system resources and causes client-side timeouts. The vulnerability affects Red Hat Enterprise Linux 6-10 and OpenShift Container Platform 4, with CVSS 2.2 reflecting low severity due to local attack vector and high complexity requirements, though the denial of service impact warrants attention in environments where SSH client availability is critical.

RemediationAI

Apply the vendor-released patch from Red Hat by upgrading libssh to the patched version released in the security advisory available at https://access.redhat.com/security/cve/CVE-2026-0967 and https://bugzilla.redhat.com/show_bug.cgi?id=2436981. Exact patched version numbers are not provided in the intelligence data; consult the advisory for specific version strings and repository channels. As an interim mitigation, restrict write access to SSH client configuration files (~/.ssh/config, ~/.ssh/known_hosts) to the owning user only, preventing unprivileged local users from injecting malicious hostnames. Additionally, educate users to avoid running SSH commands on behalf of untrusted processes or in multi-user environments where configuration files may be modified by lower-privileged accounts. Organizations using OpenShift Container Platform 4 should verify patched container images are deployed; verify via errata or Red Hat Container Catalog.

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Technical ContextAI · show details

libssh is a C library implementing the SSH protocol used across Red Hat Enterprise Linux versions 6 through 10 and OpenShift Container Platform 4 (as identified via CPE strings cpe:2.3:a:red_hat:red_hat_enterprise_linux_*). The root cause is classified under CWE-1333 (Inefficient Regular Expression Complexity), a class of vulnerabilities where untrusted input to regex engines causes pathological backtracking behavior. The match_pattern() function fails to sanitize or restrict hostname patterns before processing them through regex evaluation, allowing an attacker who controls the client-side configuration files (such as .ssh/config) or the known_hosts file to inject patterns that trigger exponential time complexity in the regex engine. This is distinct from code injection or memory corruption; instead, it is a logic flaw where algorithmic complexity is not bounded.

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Severity by source

NVD PRIMARY 5.5 MEDIUM
AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CIRCL (temporal) 2.2 LOW
Ubuntu MEDIUM
SUSE 2.2 LOW
AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L
Red Hat 2.2 LOW

Primary rating from NVD.

CVSS VectorNVD

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

Lifecycle Timeline

2
Patch released
Mar 31, 2026 - 21:13 nvd
Patch available
CVE Published
Mar 26, 2026 - 20:06 nvd
MEDIUM 5.5

DescriptionNVD

A flaw was found in libssh. A remote attacker, by controlling client configuration files or known_hosts files, could craft specific hostnames that when processed by the match_pattern() function can lead to inefficient regular expression backtracking. This can cause timeouts and resource exhaustion, resulting in a Denial of Service (DoS) for the client.

Executive ViewAI

Why It Matters

CVE-2026-0967 is a low-severity vulnerability in A flaw (CVSS 2.2). The limited severity suggests constrained impact, typically requiring specific conditions or local access for exploitation. Apply vendor updates when available as part of routine maintenance.

Business Impact: Low
Compensating Controls

Apply vendor patch during routine maintenance. Standard security controls provide adequate interim protection.

Threat Intelligence Overview

EPSS Score
0.1%
Top 80% exploitable
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment Vendor VulDB

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 No
EPSS 0.1%
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
Defer
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact
Low
Technical Impact
Partial

Priority Score

28
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +28
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.

Affected Products (CPE)NVD

cpe:2.3:a:red_hat:red_hat_enterprise_linux_10:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_6:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_7:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_8:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_9:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_openshift_container_platform_4:*:*:*:*:*:*:*:*

Related Vulnerabilities in libssh Configuration and Protocol Flaws

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CVE-2026-0966 HIGH
8.2
CVE-2026-0965 LOW
3.3
CVE-2026-0968 LOW
3.1
CVE-2026-21724 MEDIUM
5.4

More in Red Hat Enterprise Linux 10

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Heap corruption via double-free in 389-ds-base's LDAP control parsing allows an unauthenticated remote attacker to crash
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Remote code execution in Cockpit's web interface allows unauthenticated attackers to execute arbitrary commands on the h
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Remote code execution in Samba's printing subsystem allows remote attackers to inject arbitrary shell commands via craft
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7.8 Oct 06

Ghostscript can execute arbitrary shell commands with the privileges of its process when it renders a crafted PostScript
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7.8 Sep 23

Use-after-free in librsvg during rendering of crafted SVG documents with nested XInclude directives and duplicate entity
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Remote code execution and privilege escalation in HPLIP (HP Linux Imaging and Printing) affects the hpcups print filter

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Unauthenticated privilege escalation in FreeIPA (Red Hat Identity Management) allows a remote attacker to gain genuine a
CVE-2026-102560 CRITICAL
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Remote code execution in libarchive on 32-bit systems allows unauthenticated attackers to execute arbitrary code via spe

Same weakness CWE-1333 – Inefficient Regular Expression Complexity (ReDoS)

View all
CVE-2023-29486 CRITICAL POC
9.8
CVE-2023-29487 CRITICAL POC
9.1
CVE-2026-116693 HIGH POC
8.7
CVE-2026-48801 HIGH POC
8.7
CVE-2026-57584 HIGH POC
8.7
CVE-2024-58340 HIGH POC
8.7
CVE-2026-0621 HIGH POC
8.7
CVE-2026-118686 HIGH POC
8.7

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
upstream released 0.11.4
jammy released 0.9.6-2ubuntu0.22.04.6
noble released 0.10.6-2ubuntu0.3
questing released 0.11.2-1ubuntu0.2
bionic released 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6
focal released 0.9.3-2ubuntu2.5+esm3
xenial released 0.6.3-4.3ubuntu0.6+esm4
USN-8051-1 USN-8051-2

Debian

Bug #1127693
libssh
Release Status Fixed Version Urgency
bullseye vulnerable 0.9.8-0+deb11u1 -
bullseye (security) vulnerable 0.9.8-0+deb11u2 -
bookworm vulnerable 0.10.6-0+deb12u2 -
bookworm (security) vulnerable 0.10.6-0+deb12u1 -
trixie vulnerable 0.11.2-1+deb13u1 -
forky vulnerable 0.11.3-1 -
sid fixed 0.12.0-3 -
(unstable) fixed 0.12.0-1 -

SUSE

Severity: Low
Product Status
Container private-registry/harbor-trivy-adapter:1.1.1-1.40 Container suse/manager/5.0/x86_64/server:latest Image SLES15-SP7-CHOST-BYOS-Aliyun Image SLES15-SP7-CHOST-BYOS-Azure Image SLES15-SP7-CHOST-BYOS-EC2 Image SLES15-SP7-CHOST-BYOS-GCE Image SLES15-SP7-CHOST-BYOS-GDC Image SLES15-SP7-CHOST-BYOS-SAP-CCloud Image SLES15-SP7-SAP-BYOS-EC2 Image SLES15-SP7-SAP-GCE-3P Image SLES15-SP7-SAP-Hardened-BYOS-EC2 Image pr_15_7 Affected
Container suse/ltss/sle12.5/sles12sp5:8.5.205 Image SLES12-SP5-EC2-SAP-BYOS Image SLES12-SP5-SAP-Azure-LI-BYOS-Production Image SLES12-SP5-SAP-Azure-VLI-BYOS-Production Affected
Container suse/sl-micro/6.0/baremetal-os-container:latest Container suse/sl-micro/6.0/base-os-container:latest Container suse/sl-micro/6.0/kvm-os-container:latest Container suse/sl-micro/6.0/rt-os-container:latest Container suse/sl-micro/6.0/toolbox:latest Affected
Container suse/sl-micro/6.1/baremetal-os-container:2.2.1-7.59 Container suse/sl-micro/6.1/base-os-container:2.2.1-5.80 Container suse/sl-micro/6.1/kvm-os-container:2.2.1-5.85 Container suse/sl-micro/6.1/rt-os-container:2.2.1-5.73 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 SUSE-Multi-Linux-Manager-Proxy-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Server-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Server-EC2-llc Image SUSE-Multi-Linux-Manager-Server-EC2-ltd Affected
Container suse/sle-micro-rancher/5.2:latest Container suse/sle-micro/5.2/toolbox:14.2-7.11.242 Affected

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-0967 ADVISORY https://ubuntu.com/security/notices/USN-8051-1 ADVISORY https://ubuntu.com/security/notices/USN-8051-2 ADVISORY https://vuldb.com/vuln/345440 ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:0567/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:0778/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:0779/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:20524/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:20531/ REF https://access.redhat.com/errata/RHSA-2026:18160 REF https://access.redhat.com/errata/RHSA-2026:18683 REF https://access.redhat.com/security/cve/CVE-2026-0967 REF https://bugzilla.redhat.com/show_bug.cgi?id=2436981 REF https://www.libssh.org/2026/02/10/libssh-0-12-0-and-0-11-4-security-releases/

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