What’s Vulnerable › Vulnerabilities

CVE-2026-109380: modern-tar 0.3.5 through 0.8.5 Memory Exhaustion via Malformed Octal Size Field

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-12 · updated 2026-10-16
• Weakness: CWE-1284

Description

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.

Affected products

• ayuhito modern-tar: from 0.3.5 through 0.8.5

References

• 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/commit/181c8cb75351867535057817ada4802a90fe416e
• 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

Get alerted when CVE-2026-109380 or the next vulnerability affects your stack