CVE-2026-45820 PUBLISHED

Assigner: seal
Reserved: 13.05.2026 Published: 22.07.2026 Updated: 22.07.2026

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.

Metrics

CVSS 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
CVSS Score: 6.6

Product Status

Vendor 101arrowz
Product fflate
Versions Default: unaffected
  • affected from 0.4.5 to 0.4.8 (incl.)
  • affected from 0.5.0 to 0.5.3 (incl.)
  • affected from 0.6.0 to 0.6.10 (incl.)
  • affected from 0.7.0 to 0.7.4 (incl.)
  • affected from 0.8.0 to 0.8.2 (incl.)

Credits

  • Seal Security finder

References

Problem Types

  • CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop') CWE
  • CWE-400 Uncontrolled Resource Consumption CWE

Impacts

  • CAPEC-469 HTTP DoS