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Vulnerabilities

Vulnerability · CVE-2026-79591

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.

Published Sep 10, 2026 · catalog updated Oct 25, 2026 · A heap-buffer-overflow and use-after-free

Last checked Oct 25, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-79591. EPSS is 0.17%. Act only if a listed version of A heap-buffer-overflow and use-after-free is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (A heap-buffer-overflow and use-after-free).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.17%
Remediation
Advisory link
Affected products
Debian:12 r-cran-readxl · Debian:13 r-cran-readxl · Debian:14 r-cran-readxl

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Debian:12 r-cran-readxl1.4.2-1, 1.4.3-1, 1.4.4-1
  • Debian:13 r-cran-readxl1.4.5-1, 1.5.0-1, 1.5.0.1-1
  • Debian:14 r-cran-readxl0 → 1.6.0-1

How to fix CVE-2026-79591

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-79591. EPSS is 0.17%. Act only if a listed version of A heap-buffer-overflow and use-after-free is installed.

Which versions are affected?

Compare what you have installed with 1.4.2-1, 1.4.3-1, 1.4.4-1, 1.4.5-1, 1.5.0-1, 1.5.0.1-1, 0 → 1.6.0-1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.17%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 10, 2026 · Trivy Vulnerability DB

    Detected

    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.

  2. Oct 25, 2026 · Trivy Vulnerability DB

    Fix available

    r-cran-readxl fixed in 1.6.0-1

  3. Oct 25, 2026 · Trivy Vulnerability DB

    Fix available

    r-cran-readxl fixed in 1.6.0-1

  4. Oct 25, 2026 · Trivy Vulnerability DB

    Updated

    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.

Sources

  • CVE.orgVulnerability recordCVE-2026-79591

    Official CVE identifier

    cve.org
  • OpenSSF OSV / OSV ScannerPackage advisoryDEBIAN-CVE-2026-79591
    osv.dev
  • Trivy Vulnerability DBPackage advisoryDEBIAN-CVE-2026-79591

    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.

    osv.dev

References

Freshness

Last verified in this catalog Oct 25, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • OpenSSF OSV / OSV ScannerOct 25, 2026
  • CVE.orgOct 25, 2026
  • Trivy Vulnerability DBOct 25, 2026