How severe is CVE-2020-21674?

CVE-2020-21674 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-2020-21674 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-21674?

CVE-2020-21674 affects Libarchive. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-21674?

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

When was CVE-2020-21674 published?

CVE-2020-21674 was published on 2020-10-15 and last updated on 2026-06-17.

CVE-2020-21674

CVE-2020-21674 is a medium-severity vulnerability in Libarchive 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-787.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.3
EPSS exploit prediction: 2% (79th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Libarchive
Published: 2020-10-15
Last modified: 2026-06-17

Description

Heap-based buffer overflow in archive_string_append_from_wcs() (archive_string.c) in libarchive-3.4.1dev allows remote attackers to cause a denial of service (out-of-bounds write in heap memory resulting into a crash) via a crafted archive file. NOTE: this only affects users who downloaded the development code from GitHub. Users of the product's official releases are unaffected.

Frequently asked questions

What is CVE-2020-21674?: Heap-based buffer overflow in archive_string_append_from_wcs() (archive_string.c) in libarchive-3.4.1dev allows remote attackers to cause a denial of service (out-of-bounds write in heap memory resulting into a crash) via a crafted archive file. NOTE: this only affects users who downloaded the development code from GitHub. Users of the product's official releases are unaffected.
How severe is CVE-2020-21674?: CVE-2020-21674 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-2020-21674 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (79th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-21674?: CVE-2020-21674 affects Libarchive. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-21674?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-21674 published?: CVE-2020-21674 was published on 2020-10-15 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:libarchive:libarchive:3.4.1:*:*:*:*:*:*:*

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