CVE-2023-49438
Open redirect vulnerability in Flask-Security-Too
An open redirect vulnerability in the python package Flask-Security-Too <=5.3.2 allows attackers to redirect unsuspecting users to malicious sites via a crafted URL by abusing the ?next parameter on the /login and /register routes.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
6.1
An open redirect vulnerability in the python package Flask-Security-Too <=5.3.2 allows attackers to redirect unsuspecting users to malicious sites via a crafted URL by abusing the ?next parameter on the /login and /register routes.
- Record
CVE-2023-49438- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-601
- Updated
- 2026-11-02
CVE List No score
An open redirect vulnerability in the python package Flask-Security-Too <=5.3.2 allows attackers to redirect unsuspecting users to malicious sites via a crafted URL by abusing the ?next parameter on the /login and /register routes.
- Record
CVE-2023-49438- Updated
- 2026-11-02
EUVDEUVD-2023-0079 No score
An open redirect vulnerability in the python package Flask-Security-Too <=5.3.2 allows attackers to redirect unsuspecting users to malicious sites via a crafted URL by abusing the ?next parameter on the /login and /register routes.
- Record
EUVD-2023-0079- Updated
- 2026-11-02
GitHub AdvisoriesGHSA-672h-6x89-76m5
5.3
Open redirect vulnerability in Flask-Security-Too
An open redirect vulnerability in the python package Flask-Security-Too <=5.3.2 allows attackers to redirect unsuspecting users to malicious sites via a crafted URL by abusing the ?next parameter on the /login and /register routes.
Flask-Security-Too contains logic to validate that the URL specified within the next parameter is either relative or has the same network location as the requesting URL in an attempt to prevent open redirections. Previously known examples that bypassed the validation logic such as https://example/login?next=\\\\\\github.com were patched in version 4.1.0
However, examples such as https://example/login?next=/\\github.com and https://example/login?next=\\/github.com were discovered due to how web browsers normalize slashes in URLs, which makes the package vulnerable through version <=5.3.2
Additionally, with Werkzeug >=2.1.0 the autocorrect_location_header configuration was changed to False - which means that location headers in redirects are relative by default. Thus, this issue may impact applications that were previously not impacted, if they are using Werkzeug >=2.1.0 as the WSGI layer.
- Record
GHSA-672h-6x89-76m5- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N - CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-601
- Updated
- 2026-11-02
OSVGHSA-672h-6x89-76m5
5.3
Open redirect vulnerability in Flask-Security-Too
An open redirect vulnerability in the python package Flask-Security-Too <=5.3.2 allows attackers to redirect unsuspecting users to malicious sites via a crafted URL by abusing the ?next parameter on the /login and /register routes.
Flask-Security-Too contains logic to validate that the URL specified within the next parameter is either relative or has the same network location as the requesting URL in an attempt to prevent open redirections. Previously known examples that bypassed the validation logic such as https://example/login?next=\\\\\\github.com were patched in version 4.1.0
However, examples such as https://example/login?next=/\\github.com and https://example/login?next=\\/github.com were discovered due to how web browsers normalize slashes in URLs, which makes the package vulnerable through version <=5.3.2
Additionally, with Werkzeug >=2.1.0 the autocorrect_location_header configuration was changed to False - which means that location headers in redirects are relative by default. Thus, this issue may impact applications that were previously not impacted, if they are using Werkzeug >=2.1.0 as the WSGI layer.
- Record
GHSA-672h-6x89-76m5- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N - CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-601
- Updated
- 2026-11-02
OSVPYSEC-2023-248
6.1
An open redirect vulnerability in the python package Flask-Security-Too <=5.3.2 allows attackers to redirect unsuspecting users to malicious sites via a crafted URL by abusing the ?next parameter on the /login and /register routes.
- Record
PYSEC-2023-248- CVSS 3.1
- 6.1 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Updated
- 2026-11-02
OSVopenSUSE-SU-2024:13563-1 No score
python310-Flask-Security-Too-5.3.3-1.1 on GA media
These are all security issues fixed in the python310-Flask-Security-Too-5.3.3-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2024:13563-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2024:14555-1 No score
python310-Flask-Security-5.5.2-1.1 on GA media
These are all security issues fixed in the python310-Flask-Security-5.5.2-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2024:14555-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
flask-security-tooPyPI |
before 5.3.3 | 5.3.3 |
flask-security-tooPyPI |
before 5.3.3, plus listed versions 3.0.13.0.1rc13.0.1rc23.0.1rc33.0.2 Show 39 moreShow less3.1.0rc13.2.03.2.0rc13.2.0rc33.2.0rc43.3.03.3.0rc13.3.0rc23.3.0rc33.3.13.3.23.3.33.4.03.4.13.4.23.4.33.4.43.4.54.0.04.0.0rc14.0.0rc24.0.14.1.04.1.14.1.24.1.34.1.44.1.54.1.65.0.05.0.15.0.25.1.05.1.15.1.25.2.05.3.05.3.15.3.2 |
5.3.3 |
python-Flask-SecurityopenSUSE:Tumbleweed From an advisory covering 3 CVEs |
before 5.5.2-1.1 | 5.5.2-1.1 |
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| PoC in GitHub | brandon-t-elliott/CVE-2023-49438 | 2023-12-14 |
| Nuclei | Python Flask-Security-Too <=5.3.2 - Open Redirect |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, exploits, facts | ||
| first indexed | CVE List, EUVD, GitHub Advisories, Nuclei, NVD, OSV, PoC in GitHub |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-49438 is a medium vulnerability (CVSS 6.1) in Flask-security-too Project Flask-security-too, published December 26, 2023. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 1.08%, the 65th percentile. Fixed in flask-security-too 5.3.3.
References
github.com/Flask-Middleware/flask-security
github.com/brandon-t-elliott/CVE-2023-49438
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6HCYH377TPUMUHELPI36PDS2ZM4VFIXM
lists.fedoraproject.org/archives/list/[email protected]/message/6HCYH377TPUMUHELPI36PDS2ZM4VFIXM
nvd.nist.gov/vuln/detail/CVE-2023-49438
github.com/Flask-Middleware/flask-security/commit/8b5abc4d4db9926a3d76b34b8b03255effb5e712