How severe is CVE-2026-32239?

CVE-2026-32239 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-32239 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-32239?

CVE-2026-32239 affects Capnproto. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-32239?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-32239 have an EU (EUVD) identifier?

Yes. CVE-2026-32239 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-11687.

When was CVE-2026-32239 published?

CVE-2026-32239 was published on 2026-03-12 and last updated on 2026-06-17.

CVE-2026-32239

CVE-2026-32239 is a medium-severity vulnerability in Capnproto with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-190.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 6.3
EPSS exploit prediction: 0% (11th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-11687
Weakness: CWE-190
Affected product: Capnproto
Published: 2026-03-12
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-32239?: 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.
How severe is CVE-2026-32239?: CVE-2026-32239 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-32239 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-32239?: CVE-2026-32239 affects Capnproto. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-32239?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-32239 have an EU (EUVD) identifier?: Yes. CVE-2026-32239 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-11687.
When was CVE-2026-32239 published?: CVE-2026-32239 was published on 2026-03-12 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:capnproto:capnproto:*:*:*:*:*:*:*:*

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