CVE-2026-32240
MEDIUMDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 11% of all known CVEs.
References
Related Vulnerabilities
Other CWE-197 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-42475 | Critical | 9.8 | 99% | KEV + Ransom | Fix |
| CVE-2025-6965 | High | 7.7 | 75% | - | Fix |
| CVE-2024-21310 | High | 7.8 | 12% | - | Fix |
| CVE-2024-43639 | Critical | 9.8 | 8.7% | - | Fix |
| CVE-2024-38125 | High | 7.8 | 5.9% | - | Fix |
| CVE-2024-28944 | High | 8.8 | 2.4% | - | Fix |
Common questions
How do I fix CVE-2026-32240?
Upgrade capnproto on debian unstable to 1.4.0-2 or later.
Is CVE-2026-32240 being actively exploited?
Not that we know of. CVE-2026-32240 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.21% is the estimated probability that it will be exploited in the next 30 days. That is higher than 11% of all scored CVEs.
How severe is CVE-2026-32240?
CVE-2026-32240 has a CVSS v3 base score of 6.5, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-32240 affect?
Published advisories record a fix for capnproto (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-32240
Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-18.