CVE-2026-111159 in libewf
Summary
by MITRE • 10/15/2026
libewf through 20260924 contains a heap out-of-bounds read vulnerability in libewf_lef_extended_attribute_read_data() because UTF-16 name and value sizes are validated before being doubled. Attackers can supply a crafted .L01/.Lx01 file with oversized 'ea' metadata counts to crash the application or leak uninitialized heap memory through extended attributes.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified in libewf versions up to 20260924 represents a critical security flaw within the library's handling of Extended Attributes (EA) for EWF (EnCase Web Format) files, specifically located in the function libewf_lef_extended_attribute_read_data. This issue stems from an incorrect validation logic regarding UTF-16 encoded strings used for attribute names and values. In UTF-16 encoding, each character typically occupies two bytes. The vulnerability arises because the library validates the size of these name and value fields before multiplying them by two to account for the byte expansion inherent in the encoding scheme. This premature validation allows an attacker to supply a crafted .L01 or .Lx01 file containing oversized extended attribute metadata counts that bypass the initial checks but result in buffer overflows when the actual memory allocation occurs based on the doubled size.
From a technical perspective, this flaw classifies as a heap out-of-bounds read vulnerability, which aligns with Common Weakness Enumeration (CWE) identifier CWE-125: Out-of-bounds Read. The core issue is that the input validation does not accurately reflect the final memory requirements of the data structure being processed. When an attacker provides metadata counts that are large enough to pass the pre-doubling check but result in a total byte count exceeding the allocated heap buffer after doubling, the application attempts to read from memory locations outside the bounds of the intended allocation. This behavior is characteristic of improper input validation where the transformation applied to data (in this case, encoding expansion) is not accounted for during security checks.
The operational impact of this vulnerability is significant and multifaceted. Primarily, it can lead to application crashes due to segmentation faults or access violations when the program attempts to dereference invalid memory addresses. More critically, because the flaw involves a read operation rather than a write, it poses a severe risk of information disclosure. An attacker could potentially leak uninitialized heap memory contents back through extended attributes. This leaked data may contain sensitive information such as stack canaries, pointers to other objects in memory, or previously processed user data, which could be leveraged for further exploitation steps like bypassing Address Space Layout Randomization (ASLR) or constructing arbitrary code execution payloads.
In the context of cyber threat intelligence and attack frameworks, this vulnerability maps to MITRE ATT&CK technique T1083: File and Directory Discovery if used in conjunction with other tools, but more accurately reflects aspects of data exfiltration via memory leakage often associated with techniques like T1074 or specific exploitation chains involving heap spraying. The ability to read uninitialized memory is a precursor step for many advanced persistent threat (APT) activities where attackers seek to gather intelligence about the target environment before executing primary objectives.
Mitigation strategies should focus on immediate patching and defensive coding practices. Users of libewf must update to versions released after 20260924, which presumably contain fixes that validate sizes after accounting for UTF-16 expansion or implement stricter bounds checking during the allocation phase. For developers integrating this library, it is essential to ensure that all input validation routines account for character encoding multipliers before performing memory operations. Additionally, implementing runtime protection mechanisms such as AddressSanitizer (ASan) in development environments can help detect such out-of-bounds accesses early in the software lifecycle. Organizations relying on forensic tools built upon libewf should verify their dependency versions and apply security updates promptly to prevent potential exploitation through maliciously crafted EWF files designed to trigger this heap corruption scenario.