CVE-2026-62425 in libfsimage
Summary
by MITRE • 07/28/2026
[This CNA information record relates to multiple CVEs; the
text explains which aspects/vulnerabilities correspond to which CVE.]
The directory and Rock Ridge / SUSP walk in libfsimage's iso9660 driver derives several lengths directly from attacker-controlled on-disk fields without validating them:
* The directory loop itself assumes a good record length. This is CVE-2026-42494.
* The calculation of the System Use area may underflow. This is CVE-2026-42495.
* The Rock Ridge extension loop assumes a good (inner) record length. This is CVE-2026-62423.
* The Rock Ridge NM record processing assumes a good entry length. This is CVE-2026-62424.
* The Rock Ridge CE record processing assumes a good size and offset. This is CVE-2026-62425.
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Analysis
by VulDB Data Team • 07/28/2026
The vulnerabilities described in this CNA information record represent critical flaws within the libfsimage library's iso9660 driver implementation that collectively enable attackers to manipulate directory traversal and metadata processing functions through malformed on-disk structures. These issues arise from insufficient validation of attacker-controlled fields during file system parsing operations, creating multiple pathways for arbitrary code execution or system compromise when processing maliciously crafted iso9660 filesystem images.
CVE-2026-42494 specifically targets the directory loop functionality where the implementation assumes valid record length values without proper validation checks. This vulnerability falls under CWE-129 Input Validation and is closely related to ATT&CK technique T1059 Command and Scripting Interpreter for potential code execution scenarios when attacker-controlled data flows through the parsing logic. The directory traversal mechanism processes records assuming correct length fields, which allows attackers to manipulate loop boundaries and potentially cause buffer overflows or out-of-bounds memory access during filesystem navigation.
CVE-2026-42495 addresses a calculation issue in the System Use area processing that may result in integer underflow conditions. This represents a classic CWE-191 Integer Underflow vulnerability pattern that can lead to unexpected behavior when computing memory allocation sizes or loop counters. The underflow condition occurs during arithmetic operations where attacker-controlled values are used directly without proper overflow/underflow detection, potentially enabling attackers to bypass security checks or create exploitable memory corruption scenarios.
The Rock Ridge extension processing presents multiple interconnected vulnerabilities that demonstrate a pattern of insufficient validation throughout the SUSP (System Use Sharing Protocol) implementation. CVE-2026-62423 targets the Rock Ridge extension loop where inner record length assumptions are made without validation, creating similar risks to the primary directory traversal issue but within extended metadata processing functions. This vulnerability aligns with CWE-129 and represents a common weakness in file system parsers where complex metadata structures are processed without proper boundary checking.
CVE-2026-62424 focuses on the NM (Name) record processing function which assumes valid entry length values during Rock Ridge extension handling. This represents another instance of CWE-129 vulnerability where malformed data structures can cause processing failures or memory corruption. The issue occurs in the context of extended file attributes and metadata handling, demonstrating how complex file system extensions can introduce additional attack surface when proper validation is not implemented.
CVE-2026-62425 specifically targets the CE (Continuation Area) record processing where both size and offset values are assumed to be valid without checking their boundaries. This vulnerability combines elements of CWE-129 Input Validation with CWE-190 Integer Overflow/Underflow, as both fields can cause arithmetic operations to produce invalid results when attacker-controlled data is used in memory calculations or pointer arithmetic.
These vulnerabilities collectively represent a significant security risk for systems that process untrusted iso9660 filesystem images through libfsimage, as they enable attackers to construct malicious filesystem structures that can trigger various forms of memory corruption. The attack vectors align with ATT&CK tactics including T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution, where successful exploitation could lead to privilege escalation or arbitrary code execution in applications relying on this library. The cumulative impact of these issues demonstrates the importance of robust input validation and boundary checking in file system parsers, particularly when handling complex metadata structures that can be manipulated by attackers.
The root cause of all these vulnerabilities stems from inadequate defensive programming practices in the iso9660 driver implementation where attacker-controlled fields are used directly in loop conditions, memory calculations, and pointer operations without proper sanitization or validation. This pattern of insufficient input validation represents a fundamental weakness that requires comprehensive remediation through proper bounds checking, integer overflow/underflow detection, and defensive programming techniques to ensure that all on-disk structures are properly validated before being processed by the file system driver components.