# CVE-2026-86146: Apache bRPC: HTTP Request Smuggling and Header Injection via Lenient HTTP/1.1 Header Parsing


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 21 Oct 2026
- **Updated:** 21 Oct 2026
- **Also known as:** GHSA-qgcc-7cgj-hmr3

## What is CVE-2026-86146?

CVE-2026-86146 is a vulnerability in Apache bRPC, published on 21 Oct 2026. 

### Official description

Inconsistent interpretation of HTTP requests (HTTP request/response smuggling) in the bundled HTTP/1.1 parser of Apache bRPC (version < 1.18.0) on all platforms allows remote attackers to smuggle requests and inject headers when bRPC is deployed behind a proxy or load balancer that parses the same bytes differently.

Root Cause:
The bRPC fork of http-parser accepts and acts on several HTTP/1.1 header forms that a conforming front-end either rejects or interprets differently, so the framing or the header set of a message can differ between the front-end and bRPC:
1. A space before the colon of framing headers (e.g. Content-Length : 5) is accepted; the value still drives bRPC's framing while the reported field name contains the trailing space.
2. Interior spaces inside a Content-Length value (e.g. Content-Length: 1 3) are skipped, so bRPC reads 13 where a front-end reads 1 or rejects the message (same class as CVE-2022-32213 in Node.js).
3. Obsolete line folding (obs-fold, RFC 7230 3.2.4) of Content-Length and Transfer-Encoding values is accepted, so a folded framing value drives bRPC's framing while a front-end that does not unfold sees a different message.
4. Chunked trailer fields are fed to the same header callbacks as the header section and are merged into the header map like real headers. A front-end only inspects the header section, so any chunked request can smuggle fields such as Authorization or X-Forwarded-For past it.
5. Transfer-Encoding lists with optional whitespace after a comma (e.g. Transfer-Encoding: gzip, chunked) are not recognized as chunked: such requests are rejected, and responses are read until connection close instead of as chunked, causing response desync.

Affected Scenarios:
bRPC server or client communicating over HTTP/1.1 with a front proxy, load balancer, or any peer that parses the message independently. An attacker able to send requests through the front-end can desynchronize the two parsers to smuggle requests, forge headers (e.g. Authorization, X-Forwarded-For) via chunked trailers, or desynchronize responses.

How to Fix:
(Choose one of the following options)
1. Upgrade bRPC to version 1.18.0, which fixes this issue.
2. Apply this patch:  https://github.com/apache/brpc/pull/3521 

Note:
After applying the fix, the four header forms above are rejected by default and chunked trailers are dropped instead of merged into the header map. Two gflags are provided for compatibility: http_allow_obs_fold=true restores acceptance of folded Content-Length/Transfer-Encoding values, and http_strict_header_token=true additionally rejects spaces inside any header field name (not only the ones that decide framing). Legitimate clients that do not use these obsolete forms are unaffected.

Weakness: CWE-444 (Inconsistent Interpretation of HTTP Requests)

## Which versions are affected by CVE-2026-86146?


## How do I fix CVE-2026-86146?

No fix has been published for CVE-2026-86146 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-86146 being exploited?

There is no known exploitation of CVE-2026-86146 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86146 and fix it if it is affected.

What it is: CVE-2026-86146 is a vulnerability in Apache bRPC, published on 21 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-86146 in the wild and no public exploit code.

Affected product: Apache bRPC. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-86146/ (Markdown: https://insights.sbomify.com/CVE-2026-86146/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86146
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86146
- OSV: https://osv.dev/vulnerability/CVE-2026-86146

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86146/
Summaries are generated and may contain mistakes; the official description above is the record.