Vulnerability · Published Sep 10, 2026 · Assigned by mitre
CVE-2026-79591
High 7.8
In plain English
A high-severity heap buffer overflow in the r-cran-readxl package (Debian). Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)7.8High
Exploit odds (30 days)0.2%top 93.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
A heap-buffer-overflow and use-after-free vulnerability exists in the xls_getCSS() function of libxls 1.6.3 due to insufficient validation of a file-controlled font index.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | r-cran-readxl | no fix listed | DEBIAN-CVE-2026-79591 |
| Debian:13 | r-cran-readxl | no fix listed | DEBIAN-CVE-2026-79591 |
| Debian:14 | r-cran-readxl | 1.6.0-1 | DEBIAN-CVE-2026-79591 |
| Ubuntu:22.04:LTS | r-cran-readxl | no fix listed | UBUNTU-CVE-2026-79591 |
| Ubuntu:24.04:LTS | r-cran-readxl | no fix listed | UBUNTU-CVE-2026-79591 |
| Ubuntu:26.04:LTS | r-cran-readxl | no fix listed | UBUNTU-CVE-2026-79591 |
| Ubuntu:26.10 | r-cran-readxl | no fix listed | UBUNTU-CVE-2026-79591 |
Affected products (as reported)
Weakness: CWE-122 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H