CVE-2021-31408 | Server session is not invalidated when logout() helper method of Authentication module is used in Vaadin 18-19

Authentication.logout() helper in com.vaadin:flow-client versions 5.0.0 prior to 6.0.0 (Vaadin 18), and 6.0.0 through 6.0.4 (Vaadin 19.0.0 through 19.0.3) uses incorrect HTTP method, which, in combination with Spring Security CSRF protection, allows local attackers to access Fusion endpoints after the user attempted to log out.

Published: 2021-04-23 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-31408 is rated Low Risk (33.8/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.32%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-31408

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.05% 0.32% +0.27%
2 2025-12-11 0.11% 0.05% -0.06%
3 2025-11-21 — 0.11% —

Full EPSS history (11 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31408

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.3 3.1 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 1.0 5.2 [email protected]
7.1 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 1.8 5.2 [email protected]
3.3 2.0 LOW
AV:L/AC:M/Au:N/C:P/I:P/A:N Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 3.4 4.9 [email protected]

Weakness enumeration for CVE-2021-31408

GitHub Security Advisory for CVE-2021-31408

GHSA-mr8h-j9cv-4m8h · Severity: medium · Ecosystem: maven — Server session is not invalidated when logout() helper method of Authentication module is used in Vaadin 18-19

Affected software / configurations for CVE-2021-31408

Vendor Product Version Raw CPE
vaadin flow >= 5.0.0, < 6.0.0 cpe:2.3:a:vaadin:flow:*:*:*:*:*:*:*:*
vaadin flow >= 6.0.0, < 6.0.5 cpe:2.3:a:vaadin:flow:*:*:*:*:*:*:*:*
vaadin vaadin >= 19.0.0, < 19.0.4 cpe:2.3:a:vaadin:vaadin:*:*:*:*:*:*:*:*
vaadin vaadin 18.0.0 cpe:2.3:a:vaadin:vaadin:18.0.0:-:*:*:*:*:*:*

References for CVE-2021-31408

cvelogic Threat Intelligence