GHSA-2v4p-qf9q-27wj CVE-2026-84445 GO-2026-6443
gRPC-Go xDS servers: Denial of Service (DoS) via crash due to missing `:authority` and `Host` headers
High
Go
- Severity
- 8.7 / 10
- High · CVSS 4.0
- Exploit chance (EPSS)
- 0.64%
- Chance of exploitation in the next 30 days. Higher than 50.73% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Fix
1.82.2- Upgrade google.golang.org/grpc to this version or later
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 1.84.0, 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 versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| google.golang.org/grpc | < 1.82.2 |
1.82.2 |
| google.golang.org/grpc | >= 1.83.0, < 1.83.2 |
1.83.2 |
| google.golang.org/grpc | >= 1.84.0-dev, < 1.84.0-dev.0.20260825144003-d5a41119e0e3 |
1.84.0-dev.0.20260825144003-d5a41119e0e3 |
| google.golang.org/grpc | >= 1.85.0-dev, < 1.85.0-dev.0.20260825072537-93e31b48545e |
1.85.0-dev.0.20260825072537-93e31b48545e |
| google.golang.org/grpc | < 1.82.2 |
1.82.2 |
| google.golang.org/grpc | >= 1.83.0, < 1.83.2 |
1.83.2 |
| google.golang.org/grpc | >= 1.84.0-dev, < 1.84.0-dev.0.20260825144003-d5a41119e0e3 |
1.84.0-dev.0.20260825144003-d5a41119e0e3 |
| google.golang.org/grpc | >= 1.85.0-dev, < 1.85.0-dev.0.20260825072537-93e31b48545e |
1.85.0-dev.0.20260825072537-93e31b48545e |
| google.golang.org/grpc | < 1.82.2>= 1.83.0, < 1.83.2>= 1.84.0-dev, < 1.84.0-dev.0.20260825144003-d5a41119e0e3>= 1.85.0-dev, < 1.85.0-dev.0.20260825072537-93e31b48545e |
1.82.21.83.21.84.0-dev.0.20260825144003-d5a41119e0e31.85.0-dev.0.20260825072537-93e31b48545e |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
google.golang.org/grpc Go → 1.82.2
- go
go get google.golang.org/grpc@v1.82.2 && go mod tidy
Severity breakdown
CVSS 4.0 8.7
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
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- None
- Privileges required
- None
- User interaction
- None
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- None
- Availability (vulnerable system)
- High
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
- Exploit maturity
- Not defined
- Scope
- X
Weakness
CWE-129: Improper Validation of Array Index
The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.
How to prevent it
- Architecture and Design: Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
- Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server. Even though client-side checks provide minimal benefits with respect to server-side security, they are still useful. First, they can support intrusion detection. If the server receives input that should have been rejected by the client, then it may be an indication of an attack. Second, client-side error-checking can provide helpful feedback to the user about the expectations for valid input. Third, there may be a reduction in server-side processing time for accidental input errors, although this is typically a small savings.
- Requirements: Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, Ada allows the programmer to constrain the values of a variable and languages such as Java and Ruby will allow the programmer to handle exceptions when an out-of-bounds index is accessed.
- Operation, Build and Compilation: Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code. Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking. For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].
- Operation: Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX [REF-60] [REF-61]. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment. For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND [REF-1336].
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When accessing a user-controlled array index, use a stringent range of values that are within the target array. Make sure that you do not allow negative values to be used. That is, verify the minimum as well as the maximum of the range of acceptable values.
- Implementation: Be especially careful to validate all input when invoking code that crosses language boundaries, such as from an interpreted language to native code. This could create an unexpected interaction between the language boundaries. Ensure that you are not violating any of the expectations of the language with which you are interfacing. For example, even though Java may not be susceptible to buffer overflows, providing a large argument in a call to native code might trigger an overflow.
- Architecture and Design, Operation: Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
- Architecture and Design, Operation: Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
CWE-248: Uncaught Exception
An exception is thrown from a function, but it is not caught.
References
Advisories
Fixes and patches
- github.com/grpc/grpc-go/pull/9365
- github.com/grpc/grpc-go/pull/9366
- github.com/grpc/grpc-go/pull/9367
- github.com/grpc/grpc-go/commit/3822494d8ea03b992c089fd2a195f041762fffb7
- github.com/grpc/grpc-go/commit/8668b69c167df908b6b3666dcbf40992b9e932a4
- github.com/grpc/grpc-go/commit/93e31b48545e2a8aaeb6e06b47fb249f94e6297f
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-m425-mq94-257g gRPC-Go HTTP/2 Rapid Reset vulnerability | High Known exploited | Also affects google.golang.org/grpc |
| GHSA-vp52-pcj8-j9qc gRPC-Go: Heap Memory Exhaustion (OOM) via HTTP/2 DATA Frame Fragmentation | High | Also affects google.golang.org/grpc |
| GHSA-qc2q-p7wx-3px3 gRPC-Go: xDS RBAC HTTP Filter bypass via mixed-case Header Matching and gRFC A41 validation evasion | Medium | Also affects google.golang.org/grpc |
| GHSA-hrxh-6v49-42gf gRPC-Go: xDS RBAC and HTTP/2 Vulnerabilities | High | Also affects google.golang.org/grpc |
| GHSA-p77j-4mvh-x3m3 gRPC-Go has an authorization bypass via missing leading slash in :path | Critical | Also affects google.golang.org/grpc |
| GHSA-xr7q-jx4m-x55m Private tokens could appear in logs if context containing gRPC metadata is logged in github.com/grpc/grpc-go | Low | Also affects google.golang.org/grpc |
| GHSA-4w3g-jfj2-cw2q Go JOSE: Panic during CBC-HMAC processing | Medium | Same weakness, CWE-129 |
| GHSA-q97c-p368-75c4 vLLM: Out-of-vocabulary prompt token id passes input validation and triggers a CUDA device-side assert (engine crash / DoS) | Medium | Same weakness, CWE-129 |
Credits: AlekSi, akselaase, gnuletik, juliankrone, karelvanhecke, matiasinsaurralde, raphael
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