Bug 2553669 (CVE-2026-109841)

Summary:	CVE-2026-109841 undici: undici: Subresource Integrity bypass via non-lowercase algorithm tokens
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	aazores, abarbaro, akhatavk, alizardo, aos-team-art-private, asdas, ataylor, cdrage, cmah, csuconic, dbruscin, dpaolell, dschmidt, eaguilar, ebaron, eborisov, gbenhaim, gtanzill, gtully, ikhan, jbuscemi, jchui, jdelft, jhe, jlanda, jmatsuok, jsherman, jtolenti, jupierce, kshier, ktsao, kvanderr, lball, lchilton, lgarciaa, mbiarnes, mstipich, nboldt, ngough, niyer, oaljalju, pjindal, ppalepu, ppostler, prdhamdh, psrna, rbobbitt, rexwhite, rgemmell, rgodfrey, rhel-process-autobot, rushinde, sdawley, sfeifer, sghai, sidsharm, simaishi, stcannon, sthirugn, suppawar, tbish, tlavocat, twaugh, veshanka, vlaad, watson-tool-maintainers, yguenane
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in undici. The HTTP client improperly handles case sensitivity when verifying Subresource Integrity (SRI) algorithm tokens. When an application specifies an uppercase or mixed-case algorithm name, undici treats the token as unrecognized and skips verification instead of enforcing it. A remote attacker who controls the HTTP response body can exploit this flaw to deliver modified content without triggering an integrity error, bypassing intended security protections.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description OSIDB Bzimport 2026-10-15 18:42:46 UTC

undici is an HTTP client library for Node.js. In versions 7.15.0 through 7.30.0 and 8.0.0 through 8.12.1, its fetch() implementation verifies Subresource Integrity metadata by matching the algorithm token against a lowercase-only set, even though the SRI specification defines the token by its ASCII-lowercase form, so a valid but non-lowercase token such as an uppercase or mixed-case SHA256 is treated as unknown and skipped. When no recognized algorithm remains, undici treats the integrity list as empty and accepts the response, so a server returning a body that does not match the pinned digest passes the check. An attacker who controls only the response body can therefore deliver attacker-controlled bytes to an application that pinned a valid uppercase or mixed-case SRI token, with no integrity error, affecting response integrity only. The issue is fixed in undici 7.30.1 and 8.12.2, which normalize the algorithm token to ASCII lowercase before validation, and users should upgrade to one of those versions or later. As a workaround, use lowercase algorithm tokens such as sha256, sha384, or sha512 in integrity metadata.