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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
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.
Which versions are affected by CVE-2026-55406?
2 open source packages ship an affected version, including buffa.
| Package | 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.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-55406 being exploited?
There is no known exploitation of CVE-2026-55406 in the wild and no public exploit code.
Sources
Also known as GHSA-9pwq-gcrx-wghh.