CVE-2026-32240

Publication date 12 March 2026

Last updated 19 August 2026

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

6.5 · Medium

Score breakdown

Description

Cap'n Proto is a data interchange format and capability-based RPC system. Prior to 1.4.0, when using Transfer-Encoding: chunked, if a chunk's size parsed to a value of 2^64 or larger, it would be truncated to a 64-bit integer. In theory, this bug could enable HTTP request/response smuggling. This vulnerability is fixed in 1.4.0.

Read the notes from the security team

Status

Package Ubuntu Release Status
capnproto 26.04 LTS resolute
Fixed 1.1.0-2.1ubuntu0.1~esm1
25.10 questing Ignored end of life, was needs-triage
24.04 LTS noble
Fixed 1.0.1-4ubuntu0.1~esm1
22.04 LTS jammy
Fixed 0.8.0-2ubuntu2+esm1
20.04 LTS focal
Fixed 0.7.0-6ubuntu0.1~esm1
18.04 LTS bionic
Fixed 0.6.1-1ubuntu1+esm1
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected

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Notes

mrmajumder

KJ-HTTP library introduced in capnproto 0.6.0; absent in 0.4.0 (trusty) and 0.5.3 (xenial)

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
capnproto

Severity score breakdown

CVSS version:

Base score 6.3 · Medium

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

Base score 6.5 · Medium

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

References

Related Ubuntu Security Notices (USN)

    • USN-8650-1
    • Cap'n Proto vulnerabilities
    • 19 August 2026

Other references

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