CVE-2026-18508: A flaw was found in GNU tar. When extracting an archive with the --one-top-level option, hardlink targets are not confined to the designated top-level directory and may resolve rel

mediumCVSS 4.4CVE-2026-18508

A flaw was found in GNU tar. When extracting an archive with the --one-top-level option, hardlink targets are not confined to the designated top-level directory and may resolve relative to the extraction working directory. A crafted archive can create hardlinks that escape the intended boundary and, when combined with a preexisting symbolic link under the working directory, may allow writing outside that boundary during a single extraction.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: medium — CVSS 4.4
Published: 2026-08-03
Last updated: 2026-08-03
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-18508

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-185080.13% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 3% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-18508	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

medium[NEU] [UNGEPATCHT] [mittel] GNU tar: Mehrere Schwachstellen ermöglichen Manipulation von Dateiencert-bund

Recent advisories for GNU tar. When

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

medium[NEU] [UNGEPATCHT] [mittel] GNU tar: Mehrere Schwachstellen ermöglichen Manipulation von Dateiencert-bund · 2026-08-04
mediumCVE-2026-18477: A TOCTOU (Time-of-Check Time-of-Use) vulnerability in GNU tar's incremental dumpdir 'X' rename…nvd · 2026-08-03
medium[UPDATE] [medium] GNU tar: Vulnerability allows bypassing of security measurescert-bund · 2026-07-23
mediumCVE-2026-53655: node-tar applies PAX size override to intermediary GNU long-name/long-link headers, causing ta…msrc · 2026-06-09