Bug 2506034 (CVE-2026-45820)

Summary: CVE-2026-45820 fflate: fflate: Denial of Service via crafted ZIP archives
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: abarbaro, akhatavk, alizardo, amctagga, anpicker, aoconnor, aos-team-art-private, asdas, bniver, bparees, dpaolell, dschmidt, flucifre, gmeno, groman, hasun, jchui, jdelft, jfula, jhe, jlanda, jowilson, jupierce, jwong, kaycoth, kshier, ktsao, lchilton, lgarciaa, mbenjamin, mbiarnes, mhackett, nboldt, nyancey, oaljalju, omaciel, ometelka, ppalepu, ppostler, prdhamdh, psrna, ptisnovs, rhel-process-autobot, sfeifer, sghai, sidsharm, simaishi, sostapov, stcannon, suppawar, syedriko, teagle, ttakamiy, vereddy, vlaad, watson-tool-maintainers, xdharmai, yguenane
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in fflate. A remote attacker could exploit this vulnerability by providing a specially crafted ZIP archive. This archive, when processed, can lead to an infinite loop during decompression, causing a Denial of Service (DoS) condition. This occurs because a malformed central directory entry in the ZIP archive causes out-of-bounds reads, which keeps a processing loop permanently active.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2523742, 2523743    
Bug Blocks:    

Description OSIDB Bzimport 2026-07-22 08:01:22 UTC 
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.