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CVE-2026-18477 medium CVSS 4.4

Vulnerability in GNU tar's incremental dumpdir 'X' rename handling (CVE-2026-18477)

Summary

Vulnerability in GNU tar's incremental dumpdir 'X' rename handling (CVE-2026-18477). Data can be tampered with by attackers.

Original description

The description as published by the source.

A TOCTOU (Time-of-Check Time-of-Use) vulnerability in GNU tar's incremental dumpdir 'X' rename handling allows a local attacker with write access to a directory being backed up to influence the restore process if the attacker has access to the system where the restore is being performed. During restoration, files or directories may be created, renamed or overwritten outside the intended extraction directory. This could lead to unauthorized file modification or, in some cases, privilege escalation. Exploitation does not require the attacker to modify or craft the archive, and standard backup and restore workflows—including extracting into a newly created directory without using the -P option do not mitigate the issue.

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-18477 has been found in GNU tar's incremental dumpdir 'X' rename handling.
Data can be tampered with by attackers. CVSS score: 4.4/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "GNU tar's incremental dumpdir 'X' rename handling CVE-2026-18477" on the vendor's site.

CVE-2026-18477 (GNU tar's incremental dumpdir 'X' rename handling) — CWE-367 / CVSS v3 4.4
Attack vector: local
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-367) exists in GNU tar's incremental dumpdir 'X' rename handling.

📍 Affected scope

Check the vendor advisory for the affected versions of GNU tar's incremental dumpdir 'X' rename handling.

🔥 Severity

Severity: Medium (CVSS 4.4/10). Data can be tampered with by attackers.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで GNU tar's incremental dumpdir 'X' rename handling を使っているサービスとバージョンを洗い出す。

  2. 2
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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