Bug 2464122 (CVE-2026-42784)

Summary:	CVE-2026-42784 sequoia-openpgp: sequoia-openpgp: Cryptographic integrity compromise via key flag confusion
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	akhatavk, anthomas, aos-team-art-private, asdas, dbosanac, dpaolell, dschmidt, ehelms, ggainey, jdelft, jlanda, jpasqual, jreimann, jupierce, juwatts, kshier, lgarciaa, mbiarnes, mdellweg, mdessi, mhulan, mrizzi, nmoumoul, osousa, pcattana, pcreech, ppalepu, ppostler, prdhamdh, rbobbitt, rchan, rekumar, rhel-process-autobot, security-response-team, sghai, sidsharm, simaishi, smallamp, stcannon, suppawar, tmalecek, vlaad, vvoronko, watson-tool-maintainers, yguenane
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in sequoia-openpgp. The library incorrectly infers key flags for older certificates when a key flags subpacket is missing, leading to a discrepancy in how key capabilities are viewed. This key flag confusion allows an attacker to bypass the back-signature check. Consequently, an attacker can illegitimately bind an arbitrary subkey to their own certificate and forge signatures, completely compromising cryptographic integrity.	Story Points:	---
Clone Of:		Environment:
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-04-30 14:13:09 UTC

A vulnerability was found in sequoia-openpgp. The library incorrectly infers key flags from the public key algorithm for older certificates when a key flags subpacket is absent. Because SubpacketAreas::key_flags and ValidKeyAmalgamation::key_flags return different views of the key capabilities, the validation logic can be circumvented. An attacker can exploit this key flag confusion to bypass the back-signature check, allowing them to illegitimately bind an arbitrary subkey to their own certificate and forge signatures, completely compromising cryptographic integrity.

Comment 4 Jon Orris 2026-10-06 12:10:00 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:76734 https://access.redhat.com/errata/RHSA-2026:76734

Comment 5 Jon Orris 2026-10-06 13:41:18 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:76733 https://access.redhat.com/errata/RHSA-2026:76733

Comment 6 Jon Orris 2026-10-06 15:03:58 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:76735 https://access.redhat.com/errata/RHSA-2026:76735

Comment 7 Jon Orris 2026-10-07 09:07:19 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:76737 https://access.redhat.com/errata/RHSA-2026:76737

Comment 9 errata-xmlrpc 2026-11-11 05:35:28 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:98248 https://access.redhat.com/errata/RHSA-2026:98248

Comment 10 errata-xmlrpc 2026-11-12 23:46:15 UTC

This issue has been addressed in the following products:

  Red Hat Satellite 6.16 for RHEL 8
  Red Hat Satellite 6.16 for RHEL 9

Via RHSA-2026:99949 https://access.redhat.com/errata/RHSA-2026:99949

Comment 11 errata-xmlrpc 2026-11-12 23:46:55 UTC

This issue has been addressed in the following products:

  Red Hat Satellite 6.17 for RHEL 9

Via RHSA-2026:99950 https://access.redhat.com/errata/RHSA-2026:99950

Comment 12 errata-xmlrpc 2026-11-12 23:47:55 UTC

This issue has been addressed in the following products:

  Red Hat Satellite 6.18 for RHEL 9

Via RHSA-2026:99952 https://access.redhat.com/errata/RHSA-2026:99952