CVE-2026-18839: Popt-devel: popt-static: size_t underflow in singleoptionhelp
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.
Other sources
Summary: columns->max - indentLength wraps when indent exceeds width; may fail malloc or (reporter) OOB NUL write on help path.
Flow: Application option table + narrow terminal / large option width → help formatting → underflow.
Found back in popt-113-release tag.
— Red Hat
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-18839?
The severity of CVE-2026-18839 is classified as low with a score of 2.2.
How does CVE-2026-18839 affect the popt library?
CVE-2026-18839 causes an integer underflow in the popt library when handling help text for option tables exceeding terminal width.
What consequences can arise from CVE-2026-18839?
A local user can exploit CVE-2026-18839 to cause an application to crash or fail to display help, resulting in a denial of service.
How can I mitigate CVE-2026-18839?
To mitigate CVE-2026-18839, ensure that you are using an updated version of the popt library that addresses the integer underflow vulnerability.
Who is affected by CVE-2026-18839?
Local users of applications using the vulnerable versions of the popt library may be affected by CVE-2026-18839.