high7.5
CVE-2026-45820
fflate through 0.8.2 is vulnerable to denial of service via an infinite loop in unzipSync().
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | fflate | >= 0.4.5, < 0.4.9 | 0.4.9 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| 101arrowz | Fflate | through 0.8.2 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-px8p-9vwx-vf98
- https://nvd.nist.gov/vuln/detail/CVE-2026-45820
- https://github.com/101arrowz/fflate/blob/f7873560ad229c22c4b23b06c6a3806ffde77569/src/index.ts#L2714
- https://github.com/101arrowz/fflate/commit/e6d5e6e1076892f72770ac732d83c81da9f3316e
- https://github.com/101arrowz/fflate/releases/tag/v0.8.3
- https://www.npmjs.com/package/fflate