How severe is CVE-2026-84445?

No CVSS score has been assigned to CVE-2026-84445 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-84445?

CVE-2026-84445 affects the following packages: google.golang.org/grpc (Go), google.golang.org/grpc (Go), google.golang.org/grpc (Go). Ecosystems affected: Go.

How do I fix CVE-2026-84445?

Update google.golang.org/grpc to 1.82.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-84445 is resolved across your whole dependency graph.

How do I detect CVE-2026-84445 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for google.golang.org/grpc. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2026-84445 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-84445?

O3 pinpoints whether CVE-2026-84445 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2026-84445 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-84445 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was CVE-2026-84445 published, and has it been updated?

CVE-2026-84445 was published on September 8, 2026 and was last updated on September 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

Not in CISA KEV

CVE-2026-84445

Fix: grpc/grpc-go#9365

CVE-2026-84445 is a security vulnerability in google.golang.org/grpc. O3 Security confirms whether CVE-2026-84445 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

gRPC-Go xDS servers: Denial of Service (DoS) via crash due to missing `:authority` and `Host` headers

Published

Sep 8, 2026

Updated

Sep 8, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Exploitation data as of Sep 8, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

3 pkgs affected

🐹google.golang.org/grpc🐹google.golang.org/grpc🐹google.golang.org/grpc

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

A vulnerability exists in gRPC-Go servers configured with xds.NewGRPCServer() where a crafted request missing both :authority and Host headers can cause a server panic, resulting in a Denial of Service (DoS).

Servers built with xds.NewGRPCServer install an xDS routing interceptor on every RPC. This interceptor looks up the request’s :authority header to pick a virtual host. The HTTP/2 server transport previously accepted requests that had neither :authority nor Host. When this happened, the xDS routing interceptor attempted to access the first element of an empty slice of authorities, leading to an index out of bounds panic. Since the per-RPC goroutine does not recover from panics, the entire server process would terminate.

This panic occurs in the interceptor pipeline, meaning the transport credentials handshake (TLS, mTLS, or ALTS) and HTTP/2 connection establishment must complete successfully before the crafted request can reach this logic.

Insecure/Standard TLS: If the server permits insecure (plaintext) connections or standard credentials (where client certs are not checked), any unauthenticated remote attacker can trigger the crash.
mTLS / ALTS: If strict transport-level authentication is enforced at the network edge or transport layer (e.g., requiring a valid client certificate), the attacker must possess valid transport credentials to initiate the stream and trigger the panic.

Impact

An attacker can cause a complete outage of the gRPC server by sending a request missing both :authority and Host headers, provided they can successfully establish a transport connection.

Patches

The issue has been addressed in master (and backported to 1.83.2 and 1.82.2). The fix updates the HTTP/2 transport layer to reject requests missing both :authority and Host headers early, maintaining consistency with and other gRPC language implementations.

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`google.golang.org/grpc`	all versions	1.82.2
🐹Go	`google.golang.org/grpc`	≥ 1.83.0&&< 1.83.2	1.83.2
🐹Go	`google.golang.org/grpc`	≥ 1.84.0-dev&&< 1.85.0-dev.0.20260825072537-93e31b48545e	1.85.0-dev.0.20260825072537-93e31b48545e

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for google.golang.org/grpc. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update google.golang.org/grpc to 1.82.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-84445 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-84445 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-84445. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

A vulnerability exists in gRPC-Go servers configured with `xds.NewGRPCServer()` where a crafted request missing both `:authority` and `Host` headers can cause a server panic, resulting in a Denial of Service (DoS). Servers built with `xds.NewGRPCServer` install an xDS routing interceptor on every RPC. This interceptor looks up the request’s `:authority` header to pick a virtual host. The HTTP/2 server transport previously accepted requests that had neither `:authority` nor `Host`. When this happened, the xDS routing interceptor attempted to access the first element of an empty slice of author

O3 Security · Impact-Aware SCA

Is CVE-2026-84445 in your dependencies?

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