What is CVE-2026-32240?

CVE-2026-32240 is a medium-severity vulnerability in Capnproto, classified under CWE-197. CVSS score: 6.5/10. Published 2026-03-12.

How severe is CVE-2026-32240?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Capnproto

CVE-2026-32240

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.

EPSS: 0.002 (11.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 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.

Affected products

Capnproto — versions < 1.4.0

Weakness classification (CWE)

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
security-advisories@github.com (Patch, x_refsource_MISC)
security-advisories@github.com (Patch, x_refsource_MISC)
security-advisories@github.com (Product, x_refsource_MISC)
security-advisories@github.com (Product, x_refsource_MISC)

Frequently asked questions

What is CVE-2026-32240?: CVE-2026-32240 is a medium-severity vulnerability in Capnproto, classified under CWE-197. CVSS score: 6.5/10. Published 2026-03-12.
How severe is CVE-2026-32240?: Medium severity. CVSS v3 base score is 6.5 out of 10.