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.

CVSS v3 6.5 MEDIUM

6.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 2.5

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://capnproto.org/capnproto-c++-1.4.0.tar.gz	Product
https://capnproto.org/capnproto-c++-win32-1.4.0.zip	Product
https://github.com/capnproto/capnproto/commit/2744b3c012b4aa3c31cefb61ec656829fa5c0e36	Patch
https://github.com/capnproto/capnproto/commit/e929f0ba7901a6b8f4b5ba9a4db00af43288cbb0	Patch
https://github.com/capnproto/capnproto/security/advisories/GHSA-qjx3-pp3m-9jpm	Vendor Advisory

Configurations

Configuration 1 (hide)

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

History

No history.

Information

Published : 2026-03-12 20:16

Updated : 2026-03-18 16:55

NVD link : CVE-2026-32239

Mitre link : CVE-2026-32239

CVE.ORG link : CVE-2026-32239

JSON object : View

Products Affected

capnproto

capnproto

CWE

CWE-190

Integer Overflow or Wraparound

CWE-444

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

{"id": "CVE-2026-32239", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 6.5, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "LOW"}, "impactScore": 2.5, "exploitabilityScore": 3.9}], "cvssMetricV40": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 6.3, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "vectorString": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "LOW", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "LOW", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "published": "2026-03-12T20:16:05.010", "references": [{"url": "https://capnproto.org/capnproto-c++-1.4.0.tar.gz", "tags": ["Product"], "source": "security-advisories@github.com"}, {"url": "https://capnproto.org/capnproto-c++-win32-1.4.0.zip", "tags": ["Product"], "source": "security-advisories@github.com"}, {"url": "https://github.com/capnproto/capnproto/commit/2744b3c012b4aa3c31cefb61ec656829fa5c0e36", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/capnproto/capnproto/commit/e929f0ba7901a6b8f4b5ba9a4db00af43288cbb0", "tags": ["Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/capnproto/capnproto/security/advisories/GHSA-qjx3-pp3m-9jpm", "tags": ["Vendor Advisory"], "source": "security-advisories@github.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-190"}, {"lang": "en", "value": "CWE-444"}]}], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "Cap'n Proto es un formato de intercambio de datos y un sistema RPC basado en capacidades. Antes de la versi\u00f3n 1.4.0, un valor negativo de Content-Length se convert\u00eda a sin signo, trat\u00e1ndolo en su lugar como una longitud imposiblemente grande. En teor\u00eda, este error podr\u00eda permitir el contrabando de solicitudes/respuestas HTTP. Esta vulnerabilidad est\u00e1 corregida en la versi\u00f3n 1.4.0."}], "lastModified": "2026-03-18T16:55:37.693", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:capnproto:capnproto:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "8055977B-A05F-42A9-8EEF-ED19D74C1319", "versionEndExcluding": "1.4.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}