CVE-2026-109380

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.

CVSS 4.0

8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS 3.1

7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.4% chance of exploitation in the next 30 days; higher than 38% of CVEs (scores of 2026-10-25)

CWE

CWE-1284

Published

2026-10-12

Modified

2026-10-16

Record from

the NVD, synced 2026-10-19

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

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