Lxd: The Verify() method for FIDO/U2F security key types (sk-ecdsa-sha2-nistp256@openssh.com
Affects lxdSource GCVE Database
Not known to be exploited · CVSS 9.1 Critical · fixed in 20240716.00-0ubuntu1~16.04.0+esm3 : patch lxd as a priority.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 20240716.00-0ubuntu1~16.04.0+esm3, 20241011.01-0ubuntu1~18.04.0+esm3, 20250116.00-0ubuntu1~20.04.0+esm3 +8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 22 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10snapdpkg:deb/ubuntu/snapd?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSgoogle-guest-agentpkg:deb/ubuntu/google-guest-agent?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSsnapdpkg:deb/ubuntu/snapd?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu Pro 26.04 LTSgolang-go.cryptopkg:deb/ubuntu/golang-go.crypto?arch=source&distro=esm-apps/resoluteOther threats | Affected
| Fixed in
|
Ubuntu 25.10golang-go.cryptopkg:deb/ubuntu/golang-go.crypto?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10google-guest-agentpkg:deb/ubuntu/google-guest-agent?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
The Verify() method for FIDO/U2F security key types (sk-ecdsa-sha2-nistp256@openssh.com, sk-ssh-ed25519@openssh.com) 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.
References
- ubuntu.com/security/CVE-2026-39831 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-39831 (opens in a new tab)
- go.dev/issue/79566 (opens in a new tab)
- groups.google.com/g/golang-announce/c/a082jnz-LvI (opens in a new tab)
- go.dev/cl/781662 (opens in a new tab)
- pkg.go.dev/vuln/GO-2026-5019 (opens in a new tab)
- github.com/golang/crypto/commit/b61cf853a89d82cad68da5e12a6beca2116f8456 (opens in a new tab)
- ubuntu.com/security/notices/USN-8447-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8447-3 (opens in a new tab)