---
title: "CVE-2026-109380: modern-tar - Denial of Service"
description: "modern-tar 0.3.5 through 0.8.5 contains a denial of service caused by memory exhaustion via negative entry sizes from non-octal bytes in readOctal(), letting attackers exhaust process memory by supplying crafted archives, exploit requires crafted archive input."
url: https://panop.io/threat-heartbeat/CVE-2026-109380/
---

# CVE-2026-109380 modern-tar - Denial of Service

modern-tar 0.3.5 through 0.8.5 contains a denial of service caused by memory exhaustion via negative entry sizes from non-octal bytes in readOctal(), letting attackers exhaust process memory by supplying crafted archives, exploit requires crafted archive input.

CVSS base score 7.5 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.45% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-109380)

## Details

Type

Denial of Service

Impact

Denial Of Service

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Published

12 October 2026

Updated

15 October 2026

Weakness

[CWE-1284](https://cwe.mitre.org/data/definitions/1284.html)

## Vendor fix

Upgrade to the latest version beyond 0.8.5.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-109380](https://nvd.nist.gov/vuln/detail/CVE-2026-109380)
- [https://github.com/ayuhito/modern-tar](https://github.com/ayuhito/modern-tar)
- [https://github.com/ayuhito/modern-tar/blob/v0.8.5/src/tar/encoding.ts](https://github.com/ayuhito/modern-tar/blob/v0.8.5/src/tar/encoding.ts)
- [https://github.com/ayuhito/modern-tar/commit/181c8cb75351867535057817ada4802a90fe416e](https://github.com/ayuhito/modern-tar/commit/181c8cb75351867535057817ada4802a90fe416e)
- [https://github.com/ayuhito/modern-tar/pull/195](https://github.com/ayuhito/modern-tar/pull/195)
- [https://www.vulncheck.com/advisories/modern-tar-0.3.5-through-0.8.5-memory-exhaustion-via-malformed-octal-size-field](https://www.vulncheck.com/advisories/modern-tar-0.3.5-through-0.8.5-memory-exhaustion-via-malformed-octal-size-field)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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