Medium 6.6Published Jul 22, 2026

CVE-2026-45820fflate through 0.8.2 is vulnerable to denial of service via an infinite loop in unzipSync().

Updated under an hour ago (Oct 27, 2026, 1:40 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for 101arrowz fflate

Exploited in the last 30 days

fflate through 0.8.2 is vulnerable to denial of service via an infinite loop in unzipSync(). A crafted ZIP archive with a central directory entry declaring compressed_size=0xFFFFFFFF (ZIP64 sentinel) but missing the required ZIP64 extra field tag 0x0001 causes z64e() to loop indefinitely due to out-of-bounds reads returning undefined, which coerces to 0, keeping the loop condition permanently true.

CVSS: 6.6 MEDIUM (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/S:N/AU:Y/R:U/V:D/RE:M/U:Amber
Weakness (CWE): CWE-835, CWE-400
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: seal
NVD analysis: Analyzed
Record last updated: Jul 22, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

101arrowz fflate 101arrowz:fflate (from the name)	from 0.4.5 through 0.4.8; from 0.5.0 through 0.5.3; from 0.6.0 through 0.6.10; from 0.7.0 through 0.7.4; from 0.8.0 through 0.8.2	CNA record
101arrowz fflate 101arrowz:fflate	through 0.8.2	NVD

References

References

https://github.com/101arrowz/fflate/blob/f7873560ad229c22c4b23b06c6a3806ffde77569/src/index.ts#L2714	patch
https://www.npmjs.com/package/fflate	product

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.