CVE-2026-45820

Published Jul 22, 2026 CVSS 4.0 · 6.6 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-px8p-9vwx-vf98 fflate unzipSync can enter an infinite loop when parsing malformed ZIP64 archives
History
Type Values Removed Values Added
CPEs cpe:2.3:a:101arrowz:fflate:*:*:*:*:*:node.js:*:*
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Type Values Removed Values Added
Title Infinite Loop Denial of Service in fflate's unzipSync via malformed ZIP64 Headers
Type Values Removed Values Added
Title Infinite Loop Denial of Service in fflate's unzipSync via malformed ZIP64 Headers
Type Values Removed Values Added
Title Denial of Service via Infinite Loop in fflate unzipSync
Type Values Removed Values Added
Title Denial of Service via Infinite Loop in fflate unzipSync
First Time appeared 101arrowz
101arrowz fflate
Vendors & Products 101arrowz
101arrowz fflate
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description 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.
Weaknesses CWE-400
CWE-835
References
Metrics cvssV4_0

{'score': 6.6, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
seal
Published
Updated
Jul 22, 2026, 12:53 PM
Reserved
May 13, 2026, 12:03 PM
Status
Analyzed
Published
Jul 22, 2026, 8:16 AM
Modified
Oct 24, 2026, 5:10 PM