Bug 2533953 (CVE-2026-91990)

Summary: CVE-2026-91990 tornado: Tornado: Denial of Service via memory amplification in multipart parsing
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: akhatavk, anpicker, aos-team-art-private, asdas, bbrownin, bparees, dpaolell, dschmidt, ebourniv, eglynn, hasun, jdelft, jfula, jjoyce, jlanda, jowilson, jpretori, jschluet, jupierce, jwong, kaycoth, kshier, lgarciaa, lhh, mbiarnes, mburns, mgarciac, nyancey, omaciel, ometelka, ppalepu, ppostler, prdhamdh, ptisnovs, rhel-process-autobot, rjohnson, sbunciak, sghai, sidsharm, simaishi, stcannon, suppawar, syedriko, teagle, ttakamiy, vlaad, watson-tool-maintainers, xdharmai, yguenane
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in Tornado. This memory amplification vulnerability exists in the `parse_multipart_form_data` function, where multipart data is processed before validating the maximum number of parts. A remote attacker can exploit this by sending specially crafted multipart requests with numerous parts. This can lead to the creation of large temporary data structures, exhausting server memory and resulting in a Denial of Service (DoS) for the affected system.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2540168, 2540169, 2540170, 2540194, 2540195, 2540196    
Bug Blocks:    

Description OSIDB Bzimport 2026-09-15 15:52:12 UTC 
Tornado before 6.5.8 contains a memory amplification vulnerability in parse_multipart_form_data that splits multipart data before validating the max_parts limit. Attackers can send crafted multipart requests with many parts to create large transient lists, exhausting server memory and causing denial of service.