The CVSS Base score reflects an application that exposes a tchannel-go listener to untrusted network peers without an authenticated transport. The library accepts caller-supplied listeners and dialers, so an embedding application can require mutually authenticated TLS. When client certificates are required and verified, unauthenticated peers are rejected before TChannel frame parsing and the deployment should be assessed using appropriate Environmental metrics.
"}],"value":"The CVSS Base score reflects an application that exposes a tchannel-go listener to untrusted network peers without an authenticated transport. The library accepts caller-supplied listeners and dialers, so an embedding application can require mutually authenticated TLS. When client certificates are required and verified, unauthenticated peers are rejected before TChannel frame parsing and the deployment should be assessed using appropriate Environmental metrics."}],"credits":[{"lang":"en","type":"finder","value":"An external security researcher who reported this issue responsibly to Temporal Technologies"}],"descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"github.com/temporalio/tchannel-go did not validate the one-byte checksum-type field in inbound TChannel call frames. A network peer that can reach a listener can complete the standard initialization handshake and send a call request with an unsupported checksum type. The parser uses that value as an index into a four-entry checksum pool, causing an unrecovered Go panic on the connection read goroutine and terminating the hosting process. This allows remote denial of service against applications that expose the listener to untrusted peers. The impact is limited to availability; no confidentiality or integrity impact was identified.
"}],"value":"github.com/temporalio/tchannel-go did not validate the one-byte checksum-type field in inbound TChannel call frames. A network peer that can reach a listener can complete the standard initialization handshake and send a call request with an unsupported checksum type. The parser uses that value as an index into a four-entry checksum pool, causing an unrecovered Go panic on the connection read goroutine and terminating the hosting process. This allows remote denial of service against applications that expose the listener to untrusted peers. The impact is limited to availability; no confidentiality or integrity impact was identified."}],"impacts":[{"descriptions":[{"lang":"en","value":"Denial of service: one malformed TChannel call request can cause an unrecovered panic and terminate the process hosting the listener. No confidentiality or integrity impact was identified."}]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":8.7,"baseSeverity":"HIGH","exploitMaturity":"NOT_DEFINED","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"temporalio/tchannel-go reasonable worst-case network service embedding"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-129","description":"CWE-129: Improper Validation of Array Index","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-09-21T11:35:40.896Z","orgId":"61241ed8-fa44-4f23-92db-b8c443751968","shortName":"Temporal"},"references":[{"name":"First affected source revision","tags":["product"],"url":"https://github.com/temporalio/tchannel-go/commit/a6904155f628b9e602b7bc88ef489004a786f7f4"},{"name":"Vulnerable checksum-type parsing","tags":["product"],"url":"https://github.com/temporalio/tchannel-go/blob/8706a1ab5f617efd79dace7ab2d1d80cc1881df0/reqres.go#L280-L295"},{"name":"Vulnerable checksum-pool access","tags":["product"],"url":"https://github.com/temporalio/tchannel-go/blob/8706a1ab5f617efd79dace7ab2d1d80cc1881df0/checksum.go#L29-L93"},{"name":"Checksum-type validation fix","tags":["patch"],"url":"https://github.com/temporalio/tchannel-go/pull/14"},{"name":"First fixed source revision","tags":["patch"],"url":"https://github.com/temporalio/tchannel-go/commit/0cb017f6870a8420695abeb9a4560d39dadc4e2e"},{"name":"Fixed release tag v1.22.1","tags":["product"],"url":"https://github.com/temporalio/tchannel-go/tree/v1.22.1"}],"solutions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Upgrade github.com/temporalio/tchannel-go to v1.22.1 or later. The fix rejects unsupported checksum types during direct and relay frame parsing and prevents out-of-range checksum-pool access.
"}],"value":"Upgrade github.com/temporalio/tchannel-go to v1.22.1 or later. The fix rejects unsupported checksum types during direct and relay frame parsing and prevents out-of-range checksum-pool access."}],"source":{"discovery":"EXTERNAL"},"title":"temporalio/tchannel-go malformed checksum type causes process termination","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"Restrict TChannel listener access to trusted peers. Where supported by the embedding application, require mutually authenticated TLS so peers without a trusted client certificate are rejected before TChannel frame parsing. External panic-recovery middleware is not a reliable mitigation because the panic occurs on a library-created connection goroutine.
"}],"value":"Restrict TChannel listener access to trusted peers. Where supported by the embedding application, require mutually authenticated TLS so peers without a trusted client certificate are rejected before TChannel frame parsing. External panic-recovery middleware is not a reliable mitigation because the panic occurs on a library-created connection goroutine."}]}},"cveMetadata":{"assignerOrgId":"61241ed8-fa44-4f23-92db-b8c443751968","assignerShortName":"Temporal","cveId":"CVE-2026-65652","datePublished":"2026-09-21T11:35:40.896Z","dateReserved":"2026-07-22T18:08:48.925Z","dateUpdated":"2026-09-21T15:30:00.325Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-21 12:17:15","lastModifiedDate":"2026-09-22 19:40:05","problem_types":["CWE-129","CWE-129 CWE-129: Improper Validation of Array Index"],"metrics":{"cvssMetricV40":[{"source":"security@temporal.io","type":"Secondary","cvssData":{"version":"4.0","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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","baseScore":8.7,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-09-21T15:29:36.927700Z","id":"CVE-2026-65652","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"65652","Ordinal":"1","Title":"temporalio/tchannel-go malformed checksum type causes process te","CVE":"CVE-2026-65652","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"65652","Ordinal":"1","NoteData":"github.com/temporalio/tchannel-go did not validate the one-byte checksum-type field in inbound TChannel call frames. A network peer that can reach a listener can complete the standard initialization handshake and send a call request with an unsupported checksum type. The parser uses that value as an index into a four-entry checksum pool, causing an unrecovered Go panic on the connection read goroutine and terminating the hosting process. This allows remote denial of service against applications that expose the listener to untrusted peers. The impact is limited to availability; no confidentiality or integrity impact was identified.","Type":"Description","Title":"temporalio/tchannel-go malformed checksum type causes process te"}]}}}