How severe is CVE-2023-43804?

CVE-2023-43804 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2023-43804 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (65th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-43804?

CVE-2023-43804 primarily affects Python Urllib3. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-43804?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2023-43804 published?

CVE-2023-43804 was published on 2023-10-04 and last updated on 2026-06-17.

CVE-2023-43804

CVE-2023-43804 is a medium-severity vulnerability in Python Urllib3 with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-200.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
EPSS exploit prediction: 1% (65th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-200
Affected product: Python Urllib3
Published: 2023-10-04
Last modified: 2026-06-17

Description

urllib3 is a user-friendly HTTP client library for Python. urllib3 doesn't treat the `Cookie` HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a `Cookie` header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly. This issue has been patched in urllib3 version 1.26.17 or 2.0.5.

Frequently asked questions

What is CVE-2023-43804?: urllib3 is a user-friendly HTTP client library for Python. urllib3 doesn't treat the `Cookie` HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a `Cookie` header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly. This issue has been patched in urllib3 version 1.26.17 or 2.0.5.
How severe is CVE-2023-43804?: CVE-2023-43804 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2023-43804 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (65th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-43804?: CVE-2023-43804 primarily affects Python Urllib3. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-43804?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-43804 published?: CVE-2023-43804 was published on 2023-10-04 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:python:urllib3:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*

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