CVE-2026-84445 — gRPC-Go: Denial of Service (DoS) via crash due to missing `:authority` and `Host` headers in the xDS servers
gRPC-Go is the Go language implementation of gRPC. Prior to 1.82.2 and 1.83.2, servers created with xds.NewGRPCServer() allow internal/transport/http2_server.go to accept an RPC containing neither the :authority header nor the Host header, while RouteAndProcess in internal/xds/server/routing.go assumes that an authority value exists and indexes the empty slice. A remote client that can complete transport connection establishment can trigger an index-out-of-bounds panic that is not recovered by the per-RPC goroutine and terminates the entire server process. In insecure or ordinary TLS deployments the request can be unauthenticated, while strict mTLS or ALTS deployments require valid transport credentials before the malformed RPC can reach the interceptor. This issue is fixed in versions 1.82.2 and 1.83.2.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- Technical severity (high)+6
- Automatable exploitation (SSVC)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Grpc Grpc-go).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 8.7 | CVSS 4.0 | High | — | — | security-advisories@github.com via NIST National Vulnerability Database |
| 8.7 | CVSS 4.0 | High | — | — | GitHub_M via CVE Program (cve.org) e CISA ADP |
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 (score shown at the top: security-advisories@github.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · grpc/grpc-go
- SSVC assessment updated
- Record published
- CVSS changed · 8.7
- Source status changed · → Awaiting Analysis
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
10 on the record
- github.com/grpc/grpc-go/commit/3822494d8ea03b992c089fd2a195f041762fffb7
- github.com/grpc/grpc-go/commit/8668b69c167df908b6b3666dcbf40992b9e932a4
- github.com/grpc/grpc-go/security/advisories/GHSA-2v4p-qf9q-27wj
- github.com/grpc/grpc-go/issues/9354
- github.com/grpc/grpc-go/pull/9365
- github.com/grpc/grpc-go/pull/9367
- github.com/grpc/grpc-go/releases/tag/v1.83.2
- github.com/grpc/grpc-go/releases/tag/v1.82.2
- github.com/grpc/grpc-go/commit/93e31b48545e2a8aaeb6e06b47fb249f94e6297f
- github.com/grpc/grpc-go/pull/9366
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-84303 gRPC-Go: xDS RBAC HTTP Filter bypass via mixed-case Header Matching and gRFC A41 validation evasion Sep 1, 2026
- High CVE-2026-84304 gRPC-Go: Heap Memory Exhaustion (OOM) via HTTP/2 DATA Frame Fragmentation Sep 1, 2026
- Critical CVE-2026-33186 gRPC-Go has an authorization bypass via missing leading slash in :path Mar 20, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No FIRST EPSS score.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-84445 is "gRPC-Go: Denial of Service (DoS) via crash due to missing `:authority` and `Host` headers in the xDS servers", rated High. It affects Grpc-go (Grpc); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.7 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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