CVE-2026-112055 in wvWare
Summary
by MITRE • 10/18/2026
wvWare wv through 1.2.9 contains a stack-based out-of-bounds read vulnerability in wvGetPAPX_FKP and wvGetCHPX_FKP caused by an unvalidated FKP run count. Attackers can supply a crafted .doc file with a large crun value to read kilobytes past the 512-byte stack buffer, crashing applications like AbiWord.
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Analysis
by VulDB Data Team • 10/18/2026
The vulnerability identified in wvWare versions through 1.2.9 represents a critical security flaw within the document parsing engine responsible for handling Microsoft Word .doc files. Specifically, the defect resides in two internal functions, wvGetPAPX_FKP and wvGetCHPX_FKP, which are tasked with extracting paragraph and character property information from the file structure. These functions rely on an FKP run count value to determine how much data to process and copy into a fixed-size stack buffer of 512 bytes. The core technical failure is the absence of proper input validation for this crun parameter before it is used as a loop counter or size specifier during memory operations. This lack of boundary checking allows an attacker to manipulate the internal logic by supplying a maliciously crafted .doc file containing an excessively large crun value that exceeds the capacity of the allocated stack space.
From a technical perspective, this flaw constitutes a classic stack-based out-of-bounds read vulnerability. When the application processes the malformed input, it attempts to copy data based on the unvalidated count without verifying if the resulting operation will exceed the bounds of the 512-byte buffer located on the call stack. Consequently, the program reads memory locations beyond the intended limit, potentially accessing sensitive information stored in adjacent stack frames or other protected memory regions. While the primary reported impact is application instability leading to crashes in consumers like AbiWord, such out-of-bounds read conditions can also lead to information disclosure if the accessed memory contains confidential data that is subsequently leaked through error messages or core dumps. This behavior aligns with CWE-125, which defines Out-of-Bounds Read as a category of vulnerabilities where software reads past the end of an allocated buffer.
The operational impact of this vulnerability extends beyond simple denial of service. An attacker can exploit this flaw by distributing a specially crafted .doc file to unsuspecting users who utilize wvWare or applications that integrate its libraries for document conversion and viewing. Upon opening the malicious file, the application will likely crash due to memory access violations caused by reading invalid stack addresses. This results in a reliable denial of service condition against systems relying on this software component. In more complex exploitation scenarios involving related vulnerabilities, such out-of-bounds reads can serve as an information leak vector or potentially aid in bypassing security mitigations like ASLR if the leaked data reveals memory layout details. The attack scenario is consistent with ATT&CK technique T1059, specifically sub-techniques involving command and script interpreters or file manipulation tools that process untrusted input without adequate sanitization.
To mitigate this vulnerability, developers must implement strict validation checks for all integer values derived from external inputs before they are used in memory allocation or copy operations. Specifically, the crun value extracted during FKP processing should be validated against the maximum allowable size of the target buffer to ensure that no read operation exceeds 512 bytes. Input sanitization routines should reject any document structures where metadata fields indicate sizes larger than what can safely fit within the allocated stack space. Furthermore, adopting memory-safe programming practices or using static analysis tools capable of detecting out-of-bounds access patterns during development can prevent similar defects in future releases. Users affected by this issue should immediately upgrade to a patched version of wvWare that includes these boundary checks and avoid opening .doc files from untrusted sources until the patch is applied.