CVE-2021-27836

An issue was discoverered in in function xls_getWorkSheet in xls.c in libxls 1.6.2, allows...

6.5 MediumFix available

An issue was discoverered in in function xls_getWorkSheet in xls.c in libxls 1.6.2, allows attackers to cause a denial of service, via a crafted XLS file.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: Required

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: High

Exploit likelihood

1.16%Up 0.6 points since Nov 4, 2021

What each source reports

NVD Score used 6.5

An issue was discoverered in in function xls_getWorkSheet in xls.c in libxls 1.6.2, allows attackers to cause a denial of service, via a crafted XLS file.

Record: CVE-2021-27836
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS 2.0: 4.3 MediumAV:N/AC:M/Au:N/C:N/I:N/A:P
Weakness: CWE-476
Updated: 2026-11-02

CVE List No score

An issue was discoverered in in function xls_getWorkSheet in xls.c in libxls 1.6.2, allows attackers to cause a denial of service, via a crafted XLS file.

Record: CVE-2021-27836
Updated: 2026-11-02

EUVDEUVD-2021-14575 No score

An issue was discoverered in in function xls_getWorkSheet in xls.c in libxls 1.6.2, allows attackers to cause a denial of service, via a crafted XLS file.

Record: EUVD-2021-14575
Updated: 2026-11-03

GitHub AdvisoriesGHSA-gvjp-hxqq-9fc2 No score

An issue was discoverered in in function xls_getWorkSheet in xls.c in libxls 1.6.2, allows...

An issue was discoverered in in function xls_getWorkSheet in xls.c in libxls 1.6.2, allows attackers to cause a denial of service, via a crafted XLS file.

Record: GHSA-gvjp-hxqq-9fc2
Weakness: CWE-476
Updated: 2026-11-02

OSV 6.5

An issue was discoverered in in function xls_getWorkSheet in xls.c in libxls 1.6.2, allows attackers to cause a denial of service, via a crafted XLS file.

Record: CVE-2021-27836
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVDEBIAN-CVE-2021-27836 6.5

An issue was discoverered in in function xls_getWorkSheet in xls.c in libxls 1.6.2, allows attackers to cause a denial of service, via a crafted XLS file.

Record: DEBIAN-CVE-2021-27836
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated: 2026-11-02

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OSVUBUNTU-CVE-2021-27836 6.5

An issue was discoverered in in function xls_getWorkSheet in xls.c in libxls 1.6.2, allows attackers to cause a denial of service, via a crafted XLS file.

Record: UBUNTU-CVE-2021-27836
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVopenSUSE-SU-2022:0142-1 No score

Security update for libxls

This update for libxls fixes the following issues:

CVE-2021-27836: Fixed possible NULL pointer dereference via crafted XLS (boo#1192323)

Record: openSUSE-SU-2022:0142-1
Updated: 2026-11-02

OSVopenSUSE-SU-2024:12084-1 No score

libxls-devel-1.6.2-3.1 on GA media

These are all security issues fixed in the libxls-devel-1.6.2-3.1 package on the GA media of openSUSE Tumbleweed.

Record: openSUSE-SU-2024:12084-1
Updated: 2026-11-02

OSVRSEC-2023-2 No score

Denial of Service (DoS) vulnerability

The readxl R package is exposed to a vulnerability owing to its underlying use of libxls library version 1.6.2. The vulnerability originates in the xls_getWorkSheet function within xls.c in libxls. Attackers can exploit this flaw by utilizing a specially crafted XLS file, leading to a Denial of Service (DoS) attack.

Record: RSEC-2023-2
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`r-cran-readxl` Debian:12	All versions, plus listed versions 1.4.2-11.4.3-11.4.4-11.4.5-11.5.0-11.5.0.1-11.6.0-1	None known
`r-cran-readxl` Debian:13	All versions, plus listed versions 1.4.5-11.5.0-11.5.0.1-11.6.0-1	None known
`r-cran-readxl` Debian:14	All versions, plus listed versions 1.4.5-11.5.0-11.5.0.1-11.6.0-1	None known
`readxl` CRAN	1.4.1 up to 1.4.2	1.4.2
`r-cran-readxl` Ubuntu:16.04:LTS	All versions, plus listed versions 0.1.0-1	None known
`r-cran-readxl` Ubuntu:18.04:LTS	All versions, plus listed versions 1.0.0-1build11.0.0-2	None known
`r-cran-readxl` Ubuntu:20.04:LTS	All versions, plus listed versions 1.3.1-21.3.1-2build1	None known
`r-cran-readxl` Ubuntu:22.04:LTS	All versions, plus listed versions 1.3.1-2build2	None known
`r-cran-readxl` Ubuntu:24.04:LTS	All versions, plus listed versions 1.4.3-1	None known
`r-cran-readxl` Ubuntu:25.10	All versions, plus listed versions 1.4.5-1	None known

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Affected packages
Package	Affected	Fixed
`r-cran-readxl` Ubuntu:26.10	All versions, plus listed versions 1.4.5-11.5.0-1	None known
`r-cran-readxl` Ubuntu:26.04:LTS	All versions, plus listed versions 1.4.5-1	None known
`libxls` SUSE:Package Hub 15 SP3	before 1.6.2-bp153.2.6.1	1.6.2-bp153.2.6.1
`libxls` openSUSE:Leap 15.3	before 1.6.2-bp153.2.6.1	1.6.2-bp153.2.6.1

History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-27836 is a medium vulnerability (CVSS 6.5) in Libxls Project Libxls, published November 3, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.16%, the 67th percentile. Fixed in readxl 1.4.2.

References

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