Arbitrary file overwrite in tar-rs

CVE-2018-20990 → View on GitHub ↗ View on CVE.org ↗ View on NVD ↗

Description

When unpacking a tarball with the unpack_in-family of functions it's intended that only files within the specified directory are able to be written. Tarballs with hard links or symlinks, however, can be used to overwrite any file on the filesystem. Tarballs can contain multiple entries for the same file. A tarball which first contains an entry for a hard link or symlink pointing to any file on the filesystem will have the link created, and then afterwards if the same file is listed in the tarball the hard link will be rewritten and any file can be rewritten on the filesystem.

Basic information

Type
reviewed
Severity
high
Advisory on GitHub
Open advisory ↗
Repository advisory
—
Source code
Browse source ↗
Published (advisory)
2021-08-25 20:43:54 UTC
Updated
2023-06-13 21:53:49 UTC
GitHub reviewed
2021-08-19 21:24:12 UTC

EPSS Score

Score Percentile
0.30% 52.84%

CVSS Scores

Base score Version Severity Vector
7.5 3.0 —
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

Type Value
GHSA GHSA-2367-c296-3mp2 ↗
CVE CVE-2018-20990 ↗

CWEs

CWE id Name
CWE-59 Improper Link Resolution Before File Access ('Link Following')

Credits

  • tdunlap607 (analyst)

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
rust tar < 0.4.16 0.4.16 —

References

cvelogic Threat Intelligence