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Fencer Vulns
medium 6.5

CVE-2020-21674 json

Heap-based buffer overflow in archive_string_append_from_wcs() (archive_string.c) in libarchive-3.4.1dev allows remote attackers to cause a…

published 2020-10-15 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-14442

cvss
6.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.1%
EPSS 2.1% chance of exploitation in 30 days, percentile 81%
public exploits
0
none known

Summary

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.

Patch / fix

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-21674 updated cvss 7.5

libarchive: heap-based buffer overflow in archive_string_append_from_wcs function in archive_string.c

  • Red Hat Enterprise Linux 6 libarchive Red Hat Enterprise Linux 7 bsdtar, bsdcpio, libarchive
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 bsdtar, libarchive
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.08% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.