Quick answers
- Is CVE-2026-26824 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-26824 being exploited in the wild.
- How severe is CVE-2026-26824?
- Informational severity, with a CVSS score of 0, published 3 June 2026.
- Which products and versions are affected?
- Libxls through 1.6.3.
- Is there a fix for CVE-2026-26824?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-26824 attacked?
- It is attacked over the network or with local access, in a software library.
- Am I affected by CVE-2026-26824?
- Check whether you run Libxls at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A use of uninitialized memory vulnerability exists in libxls through version 1.6.3 within the OLE container parser. The root cause is located in the read_MSAT() function, where memory allocated for the Master Sector Allocation Table (MSAT) is not fully initialized before being passed to and consumed by ole2_validate_sector_chain(). An attacker can exploit this by providing a specially crafted XLS file to an application using libxls (e.g., via xls_open_buffer()). This results in undefined behavior, which can manifest as a denial-of-service (crash) or the disclosure of heap residue. The issue was identified using MemorySanitizer (MSan).
Affected products
- libxls libxls through 1.6.3
Timeline
- 2026-01-15: disclosed: Issue reported on GitHub by rmhowe425
- 2026-06-03: advisory: CVE published by NVD