PT-2026-25068 · Unknown · Cap'N Proto

Hanjeouk + 1 · Published 2026-03-12 · Updated 2026-04-21 · CVE-2026-32239

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, a negative Content-Length value was converted to unsigned, resulting in it being treated as an impossibly large length. This could potentially enable HTTP request/response smuggling. The issue is related to integer overflow in KJ-HTTP.

Recommendations Update to Cap'n Proto version 1.4.0 or later.

Exploit

Fix

Integer Overflow

HTTP Request/Response Smuggling

Weakness Enumeration

CWE-190

CWE-444

Related Identifiers

CVE-2026-32239

GHSA-QJX3-PP3M-9JPM

OPENSUSE-SU-2026:10588-1

Affected Products

Cap'N Proto

References · 17

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/32xxx/CVE-2026-32239.json · Exploit
• https://github.com/capnproto/capnproto/security/advisories/GHSA-qjx3-pp3m-9jpm · Vendor Advisory
• https://github.com/capnproto/capnproto/commit/2744b3c012b4aa3c31cefb61ec656829fa5c0e36 · Patch
• https://github.com/capnproto/capnproto/commit/e929f0ba7901a6b8f4b5ba9a4db00af43288cbb0 · Patch
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-32239 · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-32239 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-32239 · Security Note
• https://ubuntu.com/security/CVE-2026-32239 · Vendor Advisory
• https://osv.dev/vulnerability/openSUSE-SU-2026:10588-1 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2026-32239 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-32239 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2026-32239 · Security Note
• https://capnproto.org/capnproto-c++-win32-1.4.0.zip · Note
• https://twitter.com/CVEnew/status/2032230661621178876 · Twitter Post
• https://t.me/CVEtracker/47283 · Telegram Post