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GHSA-px8p-9vwx-vf98

fflate unzipSync can enter an infinite loop when parsing malformed ZIP64 archives

Source: GitHub Advisory Database (reviewed) Moderate CVE-2026-45820

Packages

EcosystemPackageAffectedFixed in
npm fflate >= 0.4.5, < 0.4.9 0.4.9
npm fflate >= 0.5.0, < 0.5.4 0.5.4
npm fflate >= 0.6.0, < 0.6.11 0.6.11
npm fflate >= 0.7.0, < 0.7.5 0.7.5
npm fflate >= 0.8.0, < 0.8.3 0.8.3

Details

As written in the advisory (Markdown source, shown as plain text).

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.

References

External links from the advisory. They lead to third-party sites.