What is the CVSS score of CVE-2026-18839?

CVE-2026-18839 has a CVSS 3.1 base score of 2.2 (Low). CVSS vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L. EPSS exploitation probability: 0.1%.

popt library CVE-2026-18839

EUVD-2026-53642 LOW

Integer Underflow (CWE-191)

2026-08-05 secalert@redhat.com

GHSA-8fjx-p4xg-vgp8

Denial Of Service Integer Overflow

2.2

CVSS 3.1 · Vendor: redhat

Severity by source

Vendor (redhat) PRIMARY

2.2 LOW

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

vuln.today AI

2.2 LOW

Local-only vector, requires triggering help output with specific terminal width; no confidentiality or integrity impact, only low availability loss.

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

4.0 AV:L/AC:H/AT:P/PR:L/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

Attack Vector

Local

Attack Complexity

High

Privileges Required

Low

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

Low

Lifecycle Timeline

Analysis Generated

Aug 05, 2026 - 21:32 vuln.today

DescriptionCVE.org

An integer underflow was found in the popt library when formatting help text for option tables that exceed the terminal width. A local user who can cause an application to print help under those conditions may cause that application to crash or fail to display help, resulting in a denial of service of the affected application.

AnalysisAI

Integer underflow in the popt command-line option parsing library can crash any application that links against it when help text is rendered under specific terminal-width conditions. Affects local, low-privileged users on systems running popt-linked applications - a broad attack surface given popt's presence across Red Hat-derived Linux distributions. Impact is strictly denial of service against the affected application; no confidentiality or integrity loss is possible. No public exploit code or active exploitation has been identified at time of analysis.

Technical ContextAI

popt is a C library for parsing command-line options, widely used as a dependency in applications on Red Hat, Fedora, CentOS, and related Linux distributions. CWE-191 (Integer Underflow) describes the root cause: when the library formats help text for option tables whose rendered width exceeds the current terminal width, an arithmetic operation produces a value that wraps below zero for an unsigned integer type, causing a miscalculation in buffer or output handling that results in application crash. The bug is triggered during the help-formatting code path - specifically when column or line calculations underflow - and is not reachable through normal option parsing, only through the help display routines.

RemediationAI

Apply updated popt packages from Red Hat when they become available via the standard Red Hat subscription channels. Monitor https://access.redhat.com/security/cve/CVE-2026-18839 and https://bugzilla.redhat.com/show_bug.cgi?id=2511010 for patch release announcements. No specific fixed version is confirmed from the available data at time of analysis - do not assume a particular version is safe until vendor confirmation. As a compensating control, restricting local shell access to untrusted users on affected systems limits the exposure, though the practical risk of this vulnerability to most environments is very low. There are no known workarounds that disable the vulnerable code path without also disabling legitimate help output functionality.