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01 Record

CVE-2026-45820

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)

MediumPUBLISHEDCNA: seal
CNA base score6.6 CVSS v4.0CVSS: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
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02 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)

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.27% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 20.1% of scored records. A rank, not a probability.
NVD base score
6.6 (CVSS v4.0), scored by the NVD independently of the CNA.
NVD 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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:N/AU:Y/R:U/V:D/RE:M/U:Amber
NVD analysis status
Analyzed. NVD last modified this record on 2026-10-24.
Red Hat severity
Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-07-22 06:57Z3 MO AGO
Last updated
2026-07-22 12:53Z3 MO AGO
Reserved
2026-05-13
Assigning CNA
seal
Record state
PUBLISHED
Severity
Medium (CVSS 6.6)
CNA 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
Weaknesses
  • CWE-400Uncontrolled Resource ConsumptionClass
  • CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')Base
  • CWE-125Out-of-bounds ReadBase
Data version
5.2
Document digest
3321efbef4f3433b38f3ed47fbe096cbfcc889b0a6fb5c426c75ee139f390633

05 Affected products

VendorProductVersionsPlatforms
101arrowzfflate0.4.5 to 0.4.8, 0.5.0 to 0.5.3, 0.6.0 to 0.6.10, 0.7.0 to 0.7.4, 0.8.0 to 0.8.2Linux, macOS, Windows

06 References