Executive brief
libxls is a library used to parse Excel spreadsheet files in binary XLS format. A maliciously crafted XLS file can trigger an out-of-bounds memory read in the summary information parser, causing the application to crash or potentially leak sensitive data from memory. Any application using libxls to open untrusted XLS files is at risk.
Technical details
This is an out-of-bounds read vulnerability (CWE-125) in the xls_dumpSummary() function, which parses OLE SummaryInformation and DocumentSummaryInformation property sets. The vulnerable code performs pointer arithmetic using file-controlled offsets (plist->sectionOffset and secHead->numProperties) without bounds validation, allowing an attacker to craft an XLS file with malicious offset values that cause the parser to read memory outside the allocated summary buffer. Attack vector is network/local (file opening); no authentication is required. The vulnerability enables information disclosure (memory leak) or denial of service (crash). A patch was merged to validate offsets before use.
Affected products
- libxls libxls 1.6.3
Timeline
- 2026-09-10: disclosed
- 2026-08-21: patched: Patch merged in PR #165