Name: CVE-2026-32239: Inconsistent Interpretation of HTTP Requests
Creator: Rapid7
Published: 2026-03-12T00:00:00.000Z
License: https://www.rapid7.com/legal/website-terms-of-use/
Keywords: CVE, CVE-2026-32239, CVSS 6.5, EPSS 0.00044

Cap'n Proto is a data interchange format and capability-based RPC system. Prior to 1.4.0, a negative Content-Length value was converted to unsigned, treating it as an impossibly large length instead. In theory, this bug could enable HTTP request/response smuggling. This vulnerability is fixed in 1.4.0.

CVSS Details

CVSS 4.0 Base Score: 6.3 (MEDIUM)
CVSS 4.0 Vector: (CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X)
CVSS 3.1 Base Score: 6.5
CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N)

Covered by Rapid7

Product	Vendor Advisory	Solution File	Added	Published
Ubuntu	—	Upgrade libcapnp-1.1.0 (Ubuntu Pro)Upgrade libcapnp-0.6.1 (Ubuntu Pro)Upgrade libcapnp-0.8.0 (Ubuntu Pro)Upgrade libcapnp-1.0.1 (Ubuntu Pro)Upgrade libcapnp-dev (Ubuntu Pro)Upgrade libcapnp-0.7.0 (Ubuntu Pro)	Aug 20, 2026	Aug 19, 2026

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CVSS Details

Covered by Rapid7

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