CVE-2018-20482

Severity: medium (CVSS 4.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2018-12-26 · updated 2026-10-14
Weakness: CWE-835

Description

GNU Tar through 1.30, when --sparse is used, mishandles file shrinkage during read access, which allows local users to cause a denial of service (infinite read loop in sparse_dump_region in sparse.c) by modifying a file that is supposed to be archived by a different user's process (e.g., a system backup running as root).

Affected products

Debian Linux: 8.0, 9.0
GNU Tar: through 1.30
openSUSE Leap: 15.0

References

http://git.savannah.gnu.org/cgit/tar.git/commit/?id=c15c42ccd1e2377945fd0414eca1a49294bff454
http://lists.gnu.org/archive/html/bug-tar/2018-12/msg00023.html
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00077.html
http://www.securityfocus.com/bid/106354
https://lists.debian.org/debian-lts-announce/2018/12/msg00023.html
https://lists.debian.org/debian-lts-announce/2021/11/msg00025.html
https://news.ycombinator.com/item?id=18745431
https://security.gentoo.org/glsa/201903-05
https://twitter.com/thatcks/status/1076166645708668928
https://utcc.utoronto.ca/~cks/space/blog/sysadmin/TarFindingTruncateBug
http://git.savannah.gnu.org/cgit/tar.git/commit/?id=c15c42ccd1e2377945fd0414eca1a49294bff454
http://lists.gnu.org/archive/html/bug-tar/2018-12/msg00023.html

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