CVE-2026-109380 (CVSS 7.5)

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.

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CVSS v3.1 Score

7.5

HIGH

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

EPSS — Exploit Prediction

0.0045

Probability of exploitation

0.37%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-1284 CWE-1284

References

Other 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

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-109380? +

CVE-2026-109380 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0045, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-109380? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-109380