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Lxd: The Verify() method for FIDO/U2F security key types ([email protected], [email protected]) did not check the User Presence…
Severity: criticalType: vulnerabilityCVE-2026-39831
The Verify() method for FIDO/U2F security key types ([email protected], [email protected]) 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.
EPSS 0.4%top 65%
Lxd: The Verify() method for FIDO/U2F security key types ([email protected], [email protected]) did not check the User Presence…
0
CriticalVulnerabilityCVE-2026-39831gcveosvubuntu-cve-2026-39831ubuntu-pro-16-04-ltsubuntu-pro-18-04-ltsubuntu-pro-20-04-ltsubuntu-22-04-ltsubuntu-pro-22-04-ltsubuntu-24-04-ltsubuntu-pro-24-04-ltsubuntu-25-10ubuntu-26-04-ltsubuntu-pro-26-04-lts
Published: 05/22/2026 (05/22/2026, 04:16:00 UTC)
Source: GCVE Database
Product: lxd
Description
The Verify() method for FIDO/U2F security key types ([email protected], [email protected]) 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.
CVSS v3.1
Score 9.1critical
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Affected software
lxd
pkg:deb/ubuntu/[email protected]~16.04.4+esm3?arch=source&distro=esm-infra-legacy/xenialAffected versions
=0.20-0ubuntu4=0.21-0ubuntu3=0.21-0ubuntu5=0.22-0ubuntu1=0.22-0ubuntu2=0.23-0ubuntu1=0.23-0ubuntu2=0.23-0ubuntu3=0.24-0ubuntu2=0.24-0ubuntu3=0.24-0ubuntu4=0.25-0ubuntu1=0.26-0ubuntu2=0.26-0ubuntu3=0.27-0ubuntu1=0.27-0ubuntu2=2.0.0~beta1-0ubuntu3=2.0.0~beta1-0ubuntu4=2.0.0~beta2-0ubuntu1=2.0.0~beta2-0ubuntu2=2.0.0~beta3-0ubuntu1=2.0.0~beta3-0ubuntu2=2.0.0~beta3-0ubuntu3=2.0.0~beta3-0ubuntu4=2.0.0~beta4-0ubuntu1=2.0.0~beta4-0ubuntu2=2.0.0~beta4-0ubuntu3=2.0.0~beta4-0ubuntu4=2.0.0~beta4-0ubuntu5=2.0.0~beta4-0ubuntu6=2.0.0~beta4-0ubuntu7=2.0.0~rc1-0ubuntu1=2.0.0~rc1-0ubuntu2=2.0.0~rc1-0ubuntu3=2.0.0~rc2-0ubuntu2=2.0.0~rc2-0ubuntu3=2.0.0~rc3-0ubuntu1=2.0.0~rc3-0ubuntu2=2.0.0~rc3-0ubuntu3=2.0.0~rc3-0ubuntu4=2.0.0~rc4-0ubuntu1=2.0.0~rc5-0ubuntu1=2.0.0~rc6-0ubuntu1=2.0.0~rc6-0ubuntu2=2.0.0~rc7-0ubuntu1=2.0.0~rc7-0ubuntu2=2.0.0~rc8-0ubuntu1=2.0.0~rc8-0ubuntu2=2.0.0~rc8-0ubuntu3=2.0.0~rc8-0ubuntu5=2.0.0~rc8-0ubuntu6=2.0.0~rc8-0ubuntu7=2.0.0~rc9-0ubuntu2=2.0.0~rc9-0ubuntu3=2.0.0~rc9-0ubuntu4=2.0.0~rc9-0ubuntu5=2.0.0-0ubuntu1=2.0.0-0ubuntu2=2.0.0-0ubuntu3=2.0.0-0ubuntu4=2.0.1-0ubuntu1~16.04.1=2.0.2-0ubuntu1~16.04.1=2.0.3-0ubuntu1~ubuntu16.04.2=2.0.4-0ubuntu1~ubuntu16.04.1=2.0.5-0ubuntu1~ubuntu16.04.1=2.0.8-0ubuntu1~ubuntu16.04.1=2.0.8-0ubuntu1~ubuntu16.04.2=2.0.9-0ubuntu1~16.04.1=2.0.9-0ubuntu1~16.04.2=2.0.10-0ubuntu1~16.04.1=2.0.10-0ubuntu1~16.04.2=2.0.11-0ubuntu1~16.04.2=2.0.11-0ubuntu1~16.04.4=2.0.11-0ubuntu1~16.04.4+esm1=2.0.11-0ubuntu1~16.04.4+esm2=2.0.11-0ubuntu1~16.04.4+esm3
snapd
pkg:deb/ubuntu/[email protected]+esm4?arch=source&distro=esm-infra-legacy/xenialAffected versions
=1.9=1.9.1.1=1.9.2=2.0=2.0.1=2.0.2=2.0.3=2.0.5=2.0.8=2.0.9=2.0.10=2.11+0.16.04=2.12+0.16.04=2.13=2.14.2~16.04=2.15.2ubuntu1=2.16ubuntu3=2.17.1ubuntu1=2.20.1ubuntu1=2.21=2.22.2=2.22.3=2.22.6=2.23.1=2.24.1=2.25=2.26.10=2.27.5=2.28.5=2.29.4.2=2.32.3.2=2.32.9=2.33.1ubuntu2=2.34.2=2.34.2ubuntu0.1=2.37.4=2.37.4ubuntu0.1=2.38=2.39.2=2.39.2ubuntu0.2=2.40=2.42.1=2.45.1=2.45.1ubuntu0.2=2.46.1=2.47.1=2.48=2.48.3=2.54.3+16.04~esm2=2.54.3+16.04.0ubuntu0.1~esm3=2.54.3+16.04.0ubuntu0.1~esm4=2.54.3+16.04.0ubuntu0.1~esm5=2.54.3+16.04.0ubuntu0.1~esm6=2.61.4ubuntu0.16.04.1+esm1=2.61.4ubuntu0.16.04.1+esm2=2.61.4ubuntu0.16.04.1+esm4
google-guest-agent
pkg:deb/ubuntu/[email protected]~16.04.0+esm3?arch=source&distro=esm-apps-legacy/xenialAffected versions
<20240716.00-0ubuntu1~16.04.0+esm3=20201217.02-0ubuntu1~16.04.0=20230426.00-0ubuntu2~16.04.3=20231004.02-0ubuntu1~16.04.1=20231004.02-0ubuntu1~16.04.2=20240716.00-0ubuntu1~16.04.0=20240716.00-0ubuntu1~16.04.0+esm1=20240716.00-0ubuntu1~16.04.0+esm2
lxd
pkg:deb/ubuntu/[email protected]~18.04.2+esm3?arch=source&distro=esm-infra/bionicAffected versions
=2.18-0ubuntu6=2.19-0ubuntu1=2.20-0ubuntu3=2.20-0ubuntu4=2.21-0ubuntu1=2.21-0ubuntu2=2.21-0ubuntu3=2.21-0ubuntu4=3.0.0~beta2-0ubuntu3=3.0.0~beta3-0ubuntu3=3.0.0~beta5-0ubuntu2=3.0.0~beta7-0ubuntu1=3.0.0-0ubuntu1=3.0.0-0ubuntu2=3.0.0-0ubuntu3=3.0.0-0ubuntu4=3.0.1-0ubuntu1~18.04.1=3.0.2-0ubuntu1~18.04.1=3.0.3-0ubuntu1~18.04.1=3.0.3-0ubuntu1~18.04.2=3.0.3-0ubuntu1~18.04.2+esm1=3.0.3-0ubuntu1~18.04.2+esm2=3.0.3-0ubuntu1~18.04.2+esm3
snapd
pkg:deb/ubuntu/[email protected]+esm4?arch=source&distro=esm-infra/bionicAffected versions
=2.28.5+17.10=2.29.4.1+18.04=2.29.4.2+18.04=2.31.1+18.04=2.32+18.04~pre5=2.32+18.04~pre6=2.32+18.04=2.32.3.2+18.04=2.32.5+18.04=2.32.8+18.04=2.32.9+18.04=2.33.1+18.04ubuntu2=2.34.2+18.04=2.34.2+18.04.1=2.37.1+18.04=2.37.1.1+18.04=2.37.4+18.04=2.37.4+18.04.1=2.38+18.04=2.39.2+18.04=2.40+18.04=2.42.1+18.04=2.45.1+18.04=2.45.1+18.04.2=2.46.1+18.04=2.47.1+18.04=2.48+18.04=2.48.3+18.04=2.49.2+18.04=2.51.1+18.04=2.54.2+18.04ubuntu1=2.54.3+18.04=2.54.3+18.04.2ubuntu0.1=2.54.3+18.04.2ubuntu0.2=2.55.5+18.04=2.57.5+18.04=2.57.5+18.04ubuntu0.1=2.58+18.04=2.58+18.04.1=2.61.4ubuntu0.18.04.1+esm1=2.61.4ubuntu0.18.04.1+esm2=2.61.4ubuntu0.18.04.1+esm4
google-guest-agent
pkg:deb/ubuntu/[email protected]~18.04.0+esm3?arch=source&distro=esm-apps/bionicAffected versions
<20241011.01-0ubuntu1~18.04.0+esm3=20201217.02-0ubuntu1~18.04.0=20210414.00-0ubuntu1~18.04.0=20210629.00-0ubuntu1~18.04.1=20220622.00-0ubuntu2~18.04.0=20220622.00-0ubuntu2~18.04.1=20230426.00-0ubuntu2~18.04.0=20231004.02-0ubuntu1~18.04.2=20231004.02-0ubuntu1~18.04.3=20240716.00-0ubuntu1~18.04.0=20241011.01-0ubuntu1~18.04.0=20241011.01-0ubuntu1~18.04.0+esm1=20241011.01-0ubuntu1~18.04.0+esm2
google-guest-agent
pkg:deb/ubuntu/[email protected]~20.04.0+esm3?arch=source&distro=esm-infra/focalAffected versions
<20250116.00-0ubuntu1~20.04.0+esm3=20201217.02-0ubuntu1~20.04.0=20210414.00-0ubuntu1~20.04.0=20210629.00-0ubuntu1~20.04.0=20220622.00-0ubuntu2~20.04.0=20220622.00-0ubuntu2~20.04.2=20230426.00-0ubuntu2~20.04.0=20231004.02-0ubuntu1~20.04.1=20231004.02-0ubuntu1~20.04.2=20231004.02-0ubuntu1~20.04.3=20231004.02-0ubuntu1~20.04.4=20240716.00-0ubuntu1~20.04.0=20241011.01-0ubuntu1~20.04.1=20250116.00-0ubuntu1~20.04.0=20250116.00-0ubuntu1~20.04.0+esm1=20250116.00-0ubuntu1~20.04.0+esm2
snapd
pkg:deb/ubuntu/[email protected]+20.04ubuntu1~esm3?arch=source&distro=esm-infra/focalAffected versions
=2.41+19.10.1=2.42.1+20.04=2.43.3+git1.8109f8=2.44~pre1+20.04=2.44+20.04=2.44.2+20.04=2.44.3+20.04=2.45.1+20.04=2.45.1+20.04.2=2.46.1+20.04=2.47.1+20.04=2.48+20.04=2.48.3+20.04=2.49.2+20.04=2.51.1+20.04ubuntu2=2.54.2+20.04ubuntu2=2.54.3+20.04=2.54.3+20.04.1=2.54.3+20.04.1ubuntu0.1=2.54.3+20.04.1ubuntu0.2=2.54.3+20.04.1ubuntu0.3=2.55.5+20.04=2.57.5+20.04=2.57.5+20.04ubuntu0.1=2.58+20.04=2.58+20.04.1=2.61.3+20.04=2.62+20.04=2.63+20.04=2.63+20.04ubuntu0.1=2.65.3+20.04=2.66.1+20.04=2.67.1+20.04=2.67.1+20.04ubuntu1~esm1=2.67.1+20.04ubuntu1~esm3
golang-go.crypto
pkg:deb/ubuntu/golang-go.crypto@1:0.0~git20200221.2aa609c-1ubuntu0.1~esm2?arch=source&distro=esm-apps/focalAffected versions
<1:0.0~git20200221.2aa609c-1ubuntu0.1~esm2=1:0.0~git20190701.4def268-2=1:0.0~git20200221.2aa609c-1=1:0.0~git20200221.2aa609c-1ubuntu0.1~esm1
google-guest-agent
pkg:deb/ubuntu/[email protected]~22.04.3?arch=source&distro=jammyAffected versions
<20250116.00-0ubuntu1~22.04.3=20210629.00-0ubuntu1=20210629.00-0ubuntu2=20220104.00-0ubuntu1=20220104.00-0ubuntu2=20220622.00-0ubuntu2~22.04.0=20220622.00-0ubuntu2~22.04.1=20230426.00-0ubuntu2~22.04.0=20231004.02-0ubuntu1~22.04.1=20231004.02-0ubuntu1~22.04.2=20231004.02-0ubuntu1~22.04.3=20231004.02-0ubuntu1~22.04.4=20231004.02-0ubuntu1~22.04.5=20240716.00-0ubuntu1~22.04.0=20241011.01-0ubuntu1~22.04.0=20250116.00-0ubuntu1~22.04.0=20250116.00-0ubuntu1~22.04.1=20250116.00-0ubuntu1~22.04.2
snapd
pkg:deb/ubuntu/[email protected]+ubuntu22.04.1?arch=source&distro=jammyAffected versions
=2.53+21.10ubuntu1=2.54.2+22.04ubuntu1=2.54.2+22.04ubuntu2=2.54.2+22.04ubuntu3=2.54.3+git19.g868fc21+22.04=2.54.3+git26.g360067e+22.04=2.55.2+22.04=2.55.2+22.04.1=2.55.3+22.04=2.55.3+22.04ubuntu1=2.55.5+22.04=2.56.2+22.04ubuntu1=2.57.4+22.04=2.57.5+22.04=2.57.5+22.04ubuntu0.1=2.58+22.04=2.58+22.04.1=2.61.3+22.04=2.62+22.04=2.63+22.04=2.63+22.04ubuntu0.1=2.65.3+22.04=2.66.1+22.04=2.67.1+22.04=2.68.5+ubuntu22.04.1=2.71+ubuntu22.04=2.72+ubuntu22.04=2.73+ubuntu22.04=2.73+ubuntu22.04.1=2.74.1+ubuntu22.04.4=2.75.2+ubuntu22.04=2.76+ubuntu22.04=2.76+ubuntu22.04.1
golang-go.crypto
pkg:deb/ubuntu/golang-go.crypto@1:0.0~git20211202.5770296-1ubuntu0.1~esm2?arch=source&distro=esm-apps/jammyAffected versions
<1:0.0~git20211202.5770296-1ubuntu0.1~esm2=1:0.0~git20201221.eec23a3-1=1:0.0~git20211202.5770296-1=1:0.0~git20211202.5770296-1ubuntu0.1~esm1
google-guest-agent
pkg:deb/ubuntu/[email protected]~24.04.4?arch=source&distro=nobleAffected versions
<20250116.00-0ubuntu1~24.04.4=20230426.00-0ubuntu3=20231004.02-0ubuntu1=20231004.02-0ubuntu3=20240213.00-0ubuntu1=20240213.00-0ubuntu2=20240213.00-0ubuntu3=20240213.00-0ubuntu3.1=20240213.00-0ubuntu3.2=20240716.00-0ubuntu1~24.04.0=20240716.00-0ubuntu1~24.04.1=20241011.01-0ubuntu1~24.04.0=20250116.00-0ubuntu1~24.04.0=20250116.00-0ubuntu1~24.04.1=20250116.00-0ubuntu1~24.04.2=20250116.00-0ubuntu1~24.04.3
snapd
pkg:deb/ubuntu/[email protected]+ubuntu24.04.1?arch=source&distro=nobleAffected versions
=2.60.4+23.10=2.61.3+24.04=2.62+24.04build1=2.63+24.04=2.63+24.04ubuntu0.1=2.63.1+24.04=2.65.3+24.04=2.66.1+24.04=2.67.1+24.04=2.68.5+ubuntu24.04.1=2.71+ubuntu24.04=2.72+ubuntu24.04=2.73+ubuntu24.04=2.73+ubuntu24.04.1=2.73+ubuntu24.04.2=2.74.1+ubuntu24.04.4=2.75.2+ubuntu24.04=2.76+ubuntu24.04=2.76+ubuntu24.04.1
golang-go.crypto
pkg:deb/ubuntu/golang-go.crypto@1:0.19.0-1ubuntu0.1~esm2?arch=source&distro=esm-apps/nobleAffected versions
<1:0.19.0-1ubuntu0.1~esm2=1:0.4.0-1=1:0.17.0-1=1:0.18.0-1=1:0.19.0-1=1:0.19.0-1ubuntu0.1~esm1
golang-go.crypto
pkg:deb/ubuntu/golang-go.crypto@1:0.25.0-1ubuntu0.1?arch=source&distro=questingAffected versions
=1:0.25.0-1=1:0.25.0-1ubuntu0.1
google-guest-agent
pkg:deb/ubuntu/[email protected]?arch=source&distro=questingAffected versions
<20250506.01-0ubuntu1.2=20250116.00-0ubuntu2=20250506.01-0ubuntu1=20250506.01-0ubuntu1.1
snapd
pkg:deb/ubuntu/[email protected]+ubuntu25.10?arch=source&distro=questingAffected versions
=2.67.1+25.04=2.68.5+ubuntu25.10.2=2.71+ubuntu25.10=2.71.1+ubuntu25.10.1=2.72+ubuntu25.10.2=2.73+ubuntu25.10=2.73+ubuntu25.10.1=2.74.1+ubuntu25.10.4=2.75.2+ubuntu25.10
google-guest-agent
pkg:deb/ubuntu/[email protected]?arch=source&distro=resoluteAffected versions
<20250506.01-0ubuntu2.1=20250506.01-0ubuntu1=20250506.01-0ubuntu2
snapd
pkg:deb/ubuntu/[email protected]+ubuntu26.04.3?arch=source&distro=resoluteAffected versions
=2.71.1+ubuntu25.10.1=2.72+ubuntu26.04.1=2.73+ubuntu26.04.1=2.74+ubuntu26.04=2.74.1+ubuntu26.04=2.74.1+ubuntu26.04.3=2.74.1+ubuntu26.04.4=2.75.2+ubuntu26.04.2=2.76+ubuntu26.04.2=2.76+ubuntu26.04.3
golang-go.crypto
pkg:deb/ubuntu/golang-go.crypto@1:0.47.0-1ubuntu0.1~esm1?arch=source&distro=esm-apps/resoluteAffected versions
<1:0.47.0-1ubuntu0.1~esm1=1:0.25.0-1=1:0.45.0-1=1:0.47.0-1
Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-39831
- Osv Schema Version
- 1.7.0
- Aliases
- []
- Ecosystems
- ["Ubuntu:Pro:16.04:LTS","Ubuntu:Pro:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:Pro:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:Pro:24.04:LTS","Ubuntu:25.10","Ubuntu:26.04:LTS","Ubuntu:Pro:26.04:LTS"]
- Database Specific Severity
- null
- Cvss Version
- 3.1
Threat ID: 6a5fd0891010f89cc219844f
Added to database: 07/21/2026, 20:03:21 UTC
Last updated: 07/31/2026, 19:22:58 UTC
Views: 25
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