CVE-2026-32239

capnproto: Cap'n Proto is a data interchange format and capability-based RPC system

CVE-2026-32239 is fixed in 6 products on 1 platform, first by capnproto 0.6.1-1ubuntu1+esm1, released March 12, 2026. It is not reported as exploited. Patch Radar priority: Routine.

Routine
CVSS
6.5
Medium
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0024
15th percentile

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.

Where it's fixed

ProductFixed inFixReleased
Linux
capnproto · Debian 14 1.4.0-2 DEBIAN-CVE-2026-32239 Mar 12, 2026
capnproto · Ubuntu 18.04.6 LTS (bionic) 0.6.1-1ubuntu1+esm1 capnproto 0.6.1-1ubuntu1+esm1 Mar 12, 2026
capnproto · Ubuntu 20.04 LTS (focal) 0.7.0-6ubuntu0.1~esm1 capnproto 0.7.0-6ubuntu0.1~esm1 Mar 12, 2026
capnproto · Ubuntu 22.04.1 LTS (jammy) 0.8.0-2ubuntu2+esm1 capnproto 0.8.0-2ubuntu2+esm1 Mar 12, 2026
capnproto · Ubuntu 24.04.5 LTS (noble) 1.0.1-4ubuntu0.1~esm1 capnproto 1.0.1-4ubuntu0.1~esm1 Mar 12, 2026
capnproto · Ubuntu 26.04.1 LTS (resolute) 1.1.0-2.1ubuntu0.1~esm1 capnproto 1.1.0-2.1ubuntu0.1~esm1 Mar 12, 2026
capnproto · opensuse-leap 16.0 1.4.0-160000.1.1 OPENSUSE-SU-2026:21062-1 Jun 26, 2026
libcapnp-0.6.1 · Ubuntu 18.04.6 LTS (bionic) 0.6.1-1ubuntu1+esm1 libcapnp-0.6.1 0.6.1-1ubuntu1+esm1 Mar 12, 2026
libcapnp-0.7.0 · Ubuntu 20.04 LTS (focal) 0.7.0-6ubuntu0.1~esm1 libcapnp-0.7.0 0.7.0-6ubuntu0.1~esm1 Mar 12, 2026
libcapnp-0.8.0 · Ubuntu 22.04.1 LTS (jammy) 0.8.0-2ubuntu2+esm1 libcapnp-0.8.0 0.8.0-2ubuntu2+esm1 Mar 12, 2026
libcapnp-1.0.1 · Ubuntu 24.04.5 LTS (noble) 1.0.1-4ubuntu0.1~esm1 libcapnp-1.0.1 1.0.1-4ubuntu0.1~esm1 Mar 12, 2026
libcapnp-1.1.0 · Ubuntu 26.04.1 LTS (resolute) 1.1.0-2.1ubuntu0.1~esm1 libcapnp-1.1.0 1.1.0-2.1ubuntu0.1~esm1 Mar 12, 2026

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