How severe is CVE-2023-23934?

CVE-2023-23934 has a CVSS 3.x base score of 2.6, rated low severity. It is exploitable over an adjacent network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2023-23934 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-23934?

CVE-2023-23934 affects Palletsprojects Werkzeug. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-23934?

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

When was CVE-2023-23934 published?

CVE-2023-23934 was published on 2023-02-14 and last updated on 2026-06-17.

CVE-2023-23934

CVE-2023-23934 is a low-severity vulnerability in Palletsprojects Werkzeug with a CVSS 3.x base score of 2.6. 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-20.

Key facts

Severity: Low (CVSS 3.x base score 2.6)
EPSS exploit prediction: 1% (40th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Palletsprojects Werkzeug
Published: 2023-02-14
Last modified: 2026-06-17

Description

Werkzeug is a comprehensive WSGI web application library. Browsers may allow "nameless" cookies that look like `=value` instead of `key=value`. A vulnerable browser may allow a compromised application on an adjacent subdomain to exploit this to set a cookie like `=__Host-test=bad` for another subdomain. Werkzeug prior to 2.2.3 will parse the cookie `=__Host-test=bad` as __Host-test=bad`. If a Werkzeug application is running next to a vulnerable or malicious subdomain which sets such a cookie using a vulnerable browser, the Werkzeug application will see the bad cookie value but the valid cookie key. The issue is fixed in Werkzeug 2.2.3.

Frequently asked questions

What is CVE-2023-23934?: Werkzeug is a comprehensive WSGI web application library. Browsers may allow "nameless" cookies that look like `=value` instead of `key=value`. A vulnerable browser may allow a compromised application on an adjacent subdomain to exploit this to set a cookie like `=__Host-test=bad` for another subdomain. Werkzeug prior to 2.2.3 will parse the cookie `=__Host-test=bad` as __Host-test=bad`. If a Werkzeug application is running next to a vulnerable or malicious subdomain which sets such a cookie using a vulnerable browser, the Werkzeug application will see the bad cookie value but the valid cookie key. The issue is fixed in Werkzeug 2.2.3.
How severe is CVE-2023-23934?: CVE-2023-23934 has a CVSS 3.x base score of 2.6, rated low severity. It is exploitable over an adjacent network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2023-23934 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-23934?: CVE-2023-23934 affects Palletsprojects Werkzeug. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-23934?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-23934 published?: CVE-2023-23934 was published on 2023-02-14 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:palletsprojects:werkzeug:*:*:*:*:*:*:*:*

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