# CVE-2026-55406: Buffa: Use-After-Free in OwnedView via Unsound 'static Lifetime Promotion in Deref

> A soundness bug in Buffa allows safe Rust code to trigger use-after-free, leading to memory corruption and information disclosure.

- **Severity:** Medium 5.9 (`CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Jul 2026
- **Updated:** 16 Jul 2026
- **Also known as:** GHSA-9pwq-gcrx-wghh

## What is CVE-2026-55406?

CVE-2026-55406 is a medium-severity use after free vulnerability in anthropics buffa, published on 16 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Buffa is a pure-Rust Protocol Buffers implementation with first-class protobuf editions support. Prior to 0.7.0, a soundness bug in the OwnedView<V> type allowed safe Rust code to trigger a use-after-free: the OwnedView::decode constructor transmuted a borrowed slice to &'static [u8], and the Deref implementation exposed the promoted 'static lifetime on borrowed view fields (such as &'static str and &'static [u8]) to callers, so the borrow checker permitted those references to outlive the OwnedView; once the OwnedView was dropped and its backing buffer freed, the references became dangling, enabling memory corruption, information disclosure of freed heap contents, and cross-thread misuse without any unsafe code in the calling application. This issue is fixed in version 0.7.0.

Weakness: CWE-416 (Use After Free), CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2026-55406?

2 open source packages ship an affected version, including buffa.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `buffa` | crates.io | All versions | 0.7.0 |
| `buffa` | crates.io | All versions | 0.7.0 |

## How do I fix CVE-2026-55406?

Upgrade buffa to 0.7.0 or later.

## Is CVE-2026-55406 being exploited?

There is no known exploitation of CVE-2026-55406 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-55406 and fix it if it is affected.

What it is: CVE-2026-55406 is a medium-severity use after free vulnerability in anthropics buffa, published on 16 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-55406 in the wild and no public exploit code.

Affected packages and fixed versions:
- buffa (crates.io): affected all versions; fixed in 0.7.0
- buffa (crates.io): affected all versions; fixed in 0.7.0

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-2026-55406/ (Markdown: https://insights.sbomify.com/CVE-2026-55406/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55406
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55406
- OSV: https://osv.dev/vulnerability/CVE-2026-55406

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55406/
Summaries are generated and may contain mistakes; the official description above is the record.