# CVE-2026-97035: Unexpected code execution and arbitrary file write via Clang -gen-* and GCC -gnat* flags in cgo in cmd/go


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 11 Nov 2026
- **Updated:** 11 Nov 2026
- **Also known as:** ALPINE-CVE-2026-97035, DEBIAN-CVE-2026-97035, GHSA-6f8j-v7cw-qxpp, GO-2026-6856, UBUNTU-CVE-2026-97035

## What is CVE-2026-97035?

CVE-2026-97035 is a vulnerability in cmd/go, published on 11 Nov 2026. 

### Official description

When using Clang or GCC, building a malicious package that uses cgo could cause unexpected code execution at build time or write files to arbitrary directories via "-gen-*" or "-gnat*" flags in "#cgo" directives. The "-g*" wildcard in the compiler and linker flag allowlists previously matched Clang's two-argument "-gen-cdb-fragment-path <dir>" flag and GCC's two-argument "-gnatO <file>" flag, permitting compilation database fragments and sidecar output files to be written to arbitrary directories and desynchronizing flag argument parsing between the go command and the compiler driver so that subsequent arguments could be passed as unvalidated positional inputs to the linker. "-gen-*" and "-gnat*" flags are now disallowed in "#cgo" compiler and linker flags.

## Which versions are affected by CVE-2026-97035?

1 open source package ship an affected version, including toolchain.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `toolchain` | Go | All versions | 1.26.11, 1.27.4 |

## How do I fix CVE-2026-97035?

Upgrade toolchain to a fixed version for your release line: 1.26.11 or 1.27.4.

## Is CVE-2026-97035 being exploited?

There is no known exploitation of CVE-2026-97035 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97035 and fix it if it is affected.

What it is: CVE-2026-97035 is a vulnerability in cmd/go, published on 11 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-97035 in the wild and no public exploit code.

Affected packages and fixed versions:
- toolchain (Go): affected all versions; fixed in 1.26.11, 1.27.4

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-2026-97035/ (Markdown: https://insights.sbomify.com/CVE-2026-97035/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97035
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97035
- OSV: https://osv.dev/vulnerability/CVE-2026-97035

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97035/
Summaries are generated and may contain mistakes; the official description above is the record.