Bug 2509479

Summary:	CVE-2026-39831 gvisor-tap-vsock: golang.org/x/crypto/ssh: Security key bypass due to missing user presence check [fedora-all]
Product:	[Fedora] Fedora	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	gvisor-tap-vsock	Assignee:	Christophe Fergeau <cfergeau>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	rawhide	CC:	cfergeau, go-sig, jnovy, lsm5
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["1537af73-e36d-4a46-a18e-3730b1edb0d7"]}
Fixed In Version:		Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
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Regression:	---	Mount Type:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2480675

Description Guilherme de Almeida Suckevicz 2026-07-30 14:35:03 UTC

Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

The Verify() method for FIDO/U2F security key types (sk-ecdsa-sha2-nistp256, sk-ssh-ed25519) did not check the User Presence flag. Signatures generated without physical touch were accepted, allowing unattended use of a hardware security key. To restore the previous behavior, return a "no-touch-required" extension in Permissions.Extensions from PublicKeyCallback.