CVE-2021-40818
scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2...
scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.
- Record
CVE-2021-40818- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 7.5 High
AV:N/AC:L/Au:N/C:P/I:P/A:P - Weakness
- CWE-120
- Updated
- 2026-11-02
CVE List No score
scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.
- Record
CVE-2021-40818- Updated
- 2026-11-02
EUVDEUVD-2021-27982 No score
scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.
- Record
EUVD-2021-27982- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-ppv3-px64-q9mx No score
scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2...
scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.
- Record
GHSA-ppv3-px64-q9mx- Weakness
- CWE-120
- Updated
- 2026-11-02
OSV
scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.
- Record
CVE-2021-40818- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVDEBIAN-CVE-2021-40818
scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.
- Record
DEBIAN-CVE-2021-40818- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2021-40818
scheme/webauthn.c in Glewlwyd SSO server through 2.5.3 has a buffer overflow during FIDO2 signature validation in webauthn registration.
- Record
UBUNTU-CVE-2021-40818- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
glewlwydDebian:12 |
before 2.5.2-3 | 2.5.2-3 |
glewlwydDebian:13 |
before 2.5.2-3 | 2.5.2-3 |
glewlwydUbuntu:18.04:LTS |
All versions, plus listed versions 1.1-2ubuntu11.2.2-11.3.1-1 |
None known |
glewlwydUbuntu:20.04:LTS |
All versions, plus listed versions 1.4.9-21.4.9-3 |
None known |
glewlwydUbuntu:22.04:LTS |
All versions, plus listed versions 2.5.2-32.6.1-12.6.1-1build1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-40818 is a critical vulnerability (CVSS 9.8) in Glewlwyd Sso Server Project Sso Server, published September 8, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.49%, the 74th percentile. Fixed in glewlwyd 2.5.2-3.