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PYSEC-2026-1379

MediumCVSS 4.3 / 10
Published Jul 7, 2026·Last modified Jul 7, 2026
Affected Components(0)

No affected components available

Description

Impact

Flask-AppBuilder prior to 4.6.2 would allow for a malicious unauthenticated actor to perform an open redirect by manipulating the Host header in HTTP requests.

Patches

Flask-AppBuilder 4.6.2 introduced the FAB_SAFE_REDIRECT_HOSTS configuration variable, which allows administrators to explicitly define which domains are considered safe for redirection.

Examples:

FAB_SAFE_REDIRECT_HOSTS = ["yourdomain.com", "sub.yourdomain.com", "*.yourcompany.com"]

Workarounds

Use a Reverse Proxy to Enforce Trusted Host Headers

References

Are there any links users can visit to find out more?

Risk Scores
Base Score
4.3

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information.

Threat Intelligence
4.0

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.19%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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