PT-2026-25069 · Capnproto+3 · Cap'N Proto

Hanjeouk + 1 · Published 2026-03-12 · Updated 2026-03-12 · CVE-2026-32240

Positive Technologies (AI Summary)

CVSS v3.1

6.5

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions Cap'n Proto versions prior to 1.4.0

Description Cap'n Proto is a data interchange format and capability-based RPC system. Prior to version 1.4.0, when using Transfer-Encoding: chunked, if a chunk's size was parsed to a value of 2^64 or larger, it would be truncated to a 64-bit integer. This could potentially enable HTTP request/response smuggling. The issue is related to the parsing of chunk sizes in HTTP requests when the Transfer-Encoding is set to chunked.

Recommendations Versions prior to 1.4.0 should be updated to version 1.4.0 or later.

Exploit

Fix

HTTP Request/Response Smuggling

Weakness Enumeration

CWE-444

CWE-197

Related Identifiers

CVE-2026-32240

GHSA-VPCQ-MX5V-32WM

Affected Products

Cap'N Proto

References · 15

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/32xxx/CVE-2026-32240.json · Exploit
• https://github.com/capnproto/capnproto/security/advisories/GHSA-vpcq-mx5v-32wm · Vendor Advisory
• https://github.com/capnproto/capnproto/commit/e929f0ba7901a6b8f4b5ba9a4db00af43288cbb0 · Patch
• https://github.com/capnproto/capnproto/commit/2744b3c012b4aa3c31cefb61ec656829fa5c0e36 · Patch
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-32240 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2026-32240 · Security Note
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-32240 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-32240 · Security Note
• https://security-tracker.debian.org/tracker/CVE-2026-32240 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-32240 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-32240 · Vendor Advisory
• https://capnproto.org/capnproto-c++-win32-1.4.0.zip · Note
• https://t.me/CVEtracker/47284 · Telegram Post
• https://twitter.com/CVEnew/status/2032230660568473821 · Twitter Post
• https://capnproto.org/capnproto-c++-1.4.0.tar.gz · Note