# CVE-2026-26825: r-cran-readxl: A use-of-uninitialized memory vulnerability exists in libxls 1.6.3 when parsing malformed XLS files

CVE-2026-26825 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-26825, released June 3, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-26825
- Priority: Routine
- CVSS: 5.3 (medium)
- EPSS: 0.0024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 3, 2026

## Description

A use-of-uninitialized memory vulnerability exists in libxls 1.6.3 when parsing malformed XLS files. The issue is reachable via xls_parseWorkBook() and is triggered by uninitialized heap memory originating from the OLE layer (ole2_read). The flaw is detectable with MemorySanitizer (MSAN) and can lead to undefined behavior, incorrect parsing logic, or potential information disclosure.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libxls opensuse-leap 16.0 | 1.6.4-bp160.1.1 | [OPENSUSE-SU-2026:22128-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22128-1.md) | Nov 7, 2026 |
| Linux | r-cran-readxl Debian 14 | 1.6.0-1 | [DEBIAN-CVE-2026-26825](https://patchblox.com/security/data/fix/linux/debian-cve-2026-26825.md) | Jun 3, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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