Bug 2509475

Summary:	CVE-2026-39831 gh: 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:	gh	Assignee:	Mikel Olasagasti Uranga <mikel>
Status:	CLOSED ERRATA	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	rawhide	CC:	go-sig, maxwell, mikel, suraj.ghimire7
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["1537af73-e36d-4a46-a18e-3730b1edb0d7"]}
Fixed In Version:	gh-2.97.0-2.fc44	Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2026-08-02 00:56:04 UTC	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:
Bug Blocks:	2480675

Description Guilherme de Almeida Suckevicz 2026-07-30 14:34:43 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.

Comment 1 Fedora Update System 2026-07-31 09:53:47 UTC

FEDORA-2026-4e77362489 (gh-2.97.0-2.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-4e77362489

Comment 2 Fedora Update System 2026-08-01 15:55:38 UTC

FEDORA-2026-4e77362489 has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-4e77362489`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-4e77362489

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 3 Fedora Update System 2026-08-02 00:56:04 UTC

FEDORA-2026-4e77362489 (gh-2.97.0-2.fc44) has been pushed to the Fedora 44 stable repository.
If problem still persists, please make note of it in this bug report.