๐Ÿ›ก๏ธ CVE-2025-43859
๐Ÿ”ด CVSS 9.5 โ€” Critical โœ… No Known Exploit CWE-444 NVD
9.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

h11 is a Python implementation of HTTP/1.1. Prior to version 0.16.0, a leniency in h11's parsing of line terminators in chunked-coding message bodies can lead to request smuggling vulnerabilities under certain conditions. This issue has been patched in version 0.16.0. Since exploitation requires the combination of buggy h11 with a buggy (reverse) proxy, fixing either component is sufficient to mitigate this issue.

Details

Severity CRITICAL
CVSS Score 9.5
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE CWE-444
Public Exploit โœ… No
Source NVD
Published 2025-04-24
Updated 2026-06-02
Modified 2026-02-04
Fix URL N/A

Affected Packages

Software From version Fixed in
h11 โ€” 0.16.0
unknown โ€” โ€”

Similar Threats

Patch Gap Protection

Running software with known vulnerabilities?

BotEraser can help reduce exposure by blocking IPs associated with exploit activity โ€” even before a patch is available.

Start Free โ†’

No credit card required  ยท  Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.