How severe is CVE-2021-33793?

CVE-2021-33793 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-33793 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33793?

CVE-2021-33793 primarily affects Foxitsoftware Foxit Reader. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-33793?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-33793 published?

CVE-2021-33793 was published on 2021-08-11 and last updated on 2026-06-17.

CVE-2021-33793

CVE-2021-33793 is a critical-severity vulnerability in Foxitsoftware Foxit Reader with a CVSS 3.x base score of 9.8. 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-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (61st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Foxitsoftware Foxit Reader
Published: 2021-08-11
Last modified: 2026-06-17

Description

Foxit Reader before 10.1.4 and PhantomPDF before 10.1.4 have an out-of-bounds write because the Cross-Reference table is mishandled during Office document conversion.

Frequently asked questions

What is CVE-2021-33793?: Foxit Reader before 10.1.4 and PhantomPDF before 10.1.4 have an out-of-bounds write because the Cross-Reference table is mishandled during Office document conversion.
How severe is CVE-2021-33793?: CVE-2021-33793 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-33793 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33793?: CVE-2021-33793 primarily affects Foxitsoftware Foxit Reader. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-33793?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-33793 published?: CVE-2021-33793 was published on 2021-08-11 and last updated on 2026-06-17.

References

https://www.foxitsoftware.com/support/security-bulletins.html

Affected products (2)

cpe:2.3:a:foxitsoftware:foxit_reader:*:*:*:*:*:*:*:*
cpe:2.3:a:foxitsoftware:phantompdf:*:*:*:*:*:*:*:*

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