---
id: CVE-2026-109380
title: >-
  modern-tar 0.3.5 through 0.8.5 contains a memory exhaustion vulnerability that
  allows attackers to produce negative entry sizes via non-octal bytes parsed by
  readOctal()
summary: >-
  modern-tar 0.3.5 through 0.8.5 contains a memory exhaustion vulnerability that
  allows attackers to produce negative entry sizes via non-octal bytes parsed by
  readOctal(). Attackers can supply a crafted, optionally gzip-compressed,
  archiv…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-1284
published: '2026-10-12'
updated: '2026-10-12'
sourceUpdated: '2026-10-12T21:17:11.153'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-109380'
references:
  - url: 'https://github.com/ayuhito/modern-tar'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/ayuhito/modern-tar/blob/v0.8.5/src/tar/encoding.ts'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/ayuhito/modern-tar/commit/181c8cb75351867535057817ada4802a90fe416e
    label: disclosure@vulncheck.com
  - url: 'https://github.com/ayuhito/modern-tar/pull/195'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/modern-tar-0.3.5-through-0.8.5-memory-exhaustion-via-malformed-octal-size-field
    label: disclosure@vulncheck.com
tags:
  - nvd
ingestedAt: '2026-10-12T22:05:40.355Z'
---

## Overview

modern-tar 0.3.5 through 0.8.5 contains a memory exhaustion vulnerability that allows attackers to produce negative entry sizes via non-octal bytes parsed by readOctal(). Attackers can supply a crafted, optionally gzip-compressed, archive to unpackTar() that buffers chunks indefinitely, exhausting process memory and suppressing later entries.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.