Bug 2521204 (CVE-2026-77354)

Summary: CVE-2026-77354 github.com/getkin/kin-openapi: kin-openapi: Denial of Service via uncontrolled resource consumption in deepObject query parameter decoding
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: akhatavk, akostadi, amasferr, amctagga, anjoseph, ansmith, aoconnor, aos-team-art-private, asdas, asyoung, bniver, crizzo, dfreiber, dhanak, dmayorov, dpaolell, drosa, drow, dsimansk, eglynn, flucifre, gmeno, gparvin, groman, jbritton, jburrell, jdelft, jhollowa, jjoyce, jlledo, jprabhak, jpretori, jsamir, jschluet, jsherril, jupierce, kaycoth, kingland, lchilton, lgarciaa, lhh, mbenjamin, mbiarnes, mburns, mgarciac, mhackett, mnovotny, orabin, pantinor, pjindal, ppalepu, ppostler, prdhamdh, prichard, rhaigner, rhel-process-autobot, rjohnson, rochandr, sausingh, sfeifer, sghai, sidsharm, sostapov, sthirugn, suppawar, tsedmik, vereddy, vkumar, vlaad, watson-tool-maintainers, wtam
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in kin-openapi, a Go project for handling OpenAPI files. An unauthenticated client can exploit this vulnerability by sending a specially crafted query with a large index in a deepObject query parameter. This forces the application to allocate multi-gigabyte memory, leading to an Out-of-Memory (OOM) error or a restart loop, effectively causing a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-08-21 21:02:01 UTC 
kin-openapi is a Go project for handling OpenAPI files. From 0.124.0 until 0.142.0, openapi3filter.sliceMapToSlice in openapi3filter/req_resp_decoder.go converts attacker-controlled sparse indexes from a deepObject query parameter into a dense slice by allocating entries from zero through the largest supplied index, after which buildResObj creates another slice of the same length. This allocation occurs before schema validation, so maxItems does not prevent it. An unauthenticated client can send a small query such as param[items][50000000]=x to an endpoint whose deepObject schema contains an array, forcing multi-gigabyte heap allocation and causing an OOM kill or restart loop. Other request-body encodings and styled parameters that do not produce bracketed integer indexes are not affected. This issue is fixed in version 0.142.0.