CVE-2026-18739 in popt
Summary
by MITRE • 08/04/2026
A flaw was found in popt, a command-line option parsing library. An off-by-one error in the poptStuffArgs function, when repeatedly called by a host application or through deep alias nesting, can lead to corruption of internal program data. This corruption could potentially enable a local attacker to execute arbitrary code if the host application then unsafely processes the altered data.
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Analysis
by VulDB Data Team • 08/04/2026
The vulnerability resides within popt, a widely-used command-line option parsing library that serves as a foundational component for numerous applications across various operating systems and environments. This flaw manifests as an off-by-one error within the poptStuffArgs function, representing a classic memory corruption issue that has significant implications for software security. The vulnerability becomes particularly dangerous when the affected library is repeatedly invoked by host applications or when deep alias nesting occurs, creating conditions where the buffer overflow can accumulate and propagate through multiple function calls.
The technical execution of this vulnerability relies on the specific nature of the off-by-one error within poptStuffArgs, which allows for one additional byte to be written beyond the allocated memory boundaries. When applications repeatedly call this function or when complex alias structures are processed, the cumulative effect of these minor overflows can gradually corrupt internal program data structures. This type of vulnerability maps directly to CWE-121, which addresses stack-based buffer overflow conditions, and also aligns with ATT&CK technique T1059.008 for command and scripting interpreter usage where the corrupted data might be processed through shell-like operations.
The operational impact of this vulnerability extends beyond simple memory corruption, as it creates potential pathways for privilege escalation and arbitrary code execution within the context of the host application. Local attackers who can control input parameters to applications utilizing popt could exploit this flaw to manipulate program flow, potentially leading to complete system compromise depending on the privileges of the target application. The vulnerability's exploitation requires careful crafting of input parameters to trigger the specific conditions that allow the off-by-one errors to compound and result in meaningful data corruption rather than mere memory corruption.
Mitigation strategies should focus on immediate patching of affected popt library versions, implementing proper bounds checking in applications that utilize this library, and conducting thorough code reviews to identify potential similar issues in other components. Organizations should also consider implementing runtime protections such as stack canaries and address space layout randomization to reduce exploit reliability. The vulnerability highlights the importance of proper input validation and memory management practices, particularly for libraries that serve as fundamental building blocks for larger applications, emphasizing the need for comprehensive security testing throughout the software development lifecycle to prevent such issues from reaching production environments.