How severe is CVE-2021-27836?

CVE-2021-27836 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-27836 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27836?

CVE-2021-27836 primarily affects Libxls Project Libxls. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-27836?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-27836 published?

CVE-2021-27836 was published on 2021-11-03 and last updated on 2026-06-17.

CVE-2021-27836

CVE-2021-27836 is a medium-severity vulnerability in Libxls Project Libxls with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-476.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.3
EPSS exploit prediction: 1% (62nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Libxls Project Libxls
Published: 2021-11-03
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-27836?: 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.
How severe is CVE-2021-27836?: CVE-2021-27836 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-27836 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27836?: CVE-2021-27836 primarily affects Libxls Project Libxls. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-27836?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-27836 published?: CVE-2021-27836 was published on 2021-11-03 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:libxls_project:libxls:1.6.2:-:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*

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