How severe is CVE-2021-37220?

CVE-2021-37220 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-37220 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-37220?

CVE-2021-37220 primarily affects Artifex Mupdf. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-37220?

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

When was CVE-2021-37220 published?

CVE-2021-37220 was published on 2021-07-21 and last updated on 2026-06-17.

CVE-2021-37220

CVE-2021-37220 is a medium-severity vulnerability in Artifex Mupdf with a CVSS 3.x base score of 5.5. 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-787.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v2: 4.3
EPSS exploit prediction: 1% (68th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Artifex Mupdf
Published: 2021-07-21
Last modified: 2026-06-17

Description

MuPDF through 1.18.1 has an out-of-bounds write because the cached color converter does not properly consider the maximum key size of a hash table. This can, for example, be seen with crafted "mutool draw" input.

Frequently asked questions

What is CVE-2021-37220?: MuPDF through 1.18.1 has an out-of-bounds write because the cached color converter does not properly consider the maximum key size of a hash table. This can, for example, be seen with crafted "mutool draw" input.
How severe is CVE-2021-37220?: CVE-2021-37220 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-37220 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-37220?: CVE-2021-37220 primarily affects Artifex Mupdf. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-37220?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-37220 published?: CVE-2021-37220 was published on 2021-07-21 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:artifex:mupdf:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*

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CVE-2011-0341 — Critical (CVSS 9.3): Stack-based buffer overflow in the pdfmoz_onmouse function in apps/mozilla/moz_main.c in the MuPDF plug-in 2008.09.02…
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CVE-2012-5340 — High (CVSS 7.8): SumatraPDF 2.1.1/MuPDF 1.0 allows remote attackers to cause an Integer Overflow in the lex_number() function via a…
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