CVE-2025-43859

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

• ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.59% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 48.1% of scored records. A rank, not a probability.

NVD base score

9.1 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

NVD analysis status

Deferred. NVD last modified this record on 2026-06-17.

Red Hat severity

Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2025-04-24 18:15Z1 YR AGO

Last updated

2025-04-24 19:02Z1 YR AGO

Reserved

2025-04-17

Assigning CNA

GitHub_M

Record state

PUBLISHED

Severity

Critical (CVSS 9.1)

CNA CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Weaknesses

• CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')Base

Data version

5.1

Document digest

4ea9c7739f0be4992727056b97fad9436f188ca1a0aefb19e7dc9771d70b5bb9

• github.comhttps://github.com/python-hyper/h11/security/advisories/GHSA-vqfr-h8mv-ghfjx_refsource_CONFIRM
• github.comhttps://github.com/python-hyper/h11/commit/114803a29ce50116dc47951c690ad4892b1a36edx_refsource_MISC