CVE-2026-55406
Buffa: Use-After-Free in OwnedView via Unsound 'static Lifetime Promotion in Deref
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.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
5.9
Buffa: Use-After-Free in OwnedView via Unsound 'static Lifetime Promotion in Deref
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.
- Record
CVE-2026-55406- CVSS 4.0
- 5.9 Medium
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 - Weakness
- CWE-200, CWE-416
- Updated
- 2026-11-02
EUVDEUVD-2026-44949
5.9
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.
- Record
EUVD-2026-44949- CVSS 4.0
- 5.9 Medium
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-9pwq-gcrx-wghh
5.9
Buffa has a Use-After-Free in OwnedView via Unsound 'static Lifetime Promotion in Deref
A soundness bug in buffa's OwnedView<V> 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. Because these references appeared to be 'static, the borrow checker permitted them to outlive the OwnedView; once the OwnedView was dropped and its backing buffer freed, those references became dangling, enabling memory corruption, information disclosure of freed heap contents, and cross-thread misuse — all without any unsafe code in the calling application. Users are advised to update to the latest patched version of buffa.
Thank you to hackerone.com/suul for reporting this issue.
- Record
GHSA-9pwq-gcrx-wghh- CVSS 4.0
- 5.9 Medium
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 - Weakness
- CWE-200, CWE-416
- Updated
- 2026-11-02
NVD
5.9
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.
- Record
CVE-2026-55406- CVSS 4.0
- 5.9 Medium
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/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 - Weakness
- CWE-200, CWE-416
- Updated
- 2026-11-02
OSV
5.9
Buffa: Use-After-Free in OwnedView via Unsound 'static Lifetime Promotion in Deref
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.
- Record
CVE-2026-55406- CVSS 4.0
- 5.9 Medium
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 - Weakness
- CWE-200, CWE-416
- Updated
- 2026-11-02
OSVGHSA-9pwq-gcrx-wghh
5.9
Buffa has a Use-After-Free in OwnedView via Unsound 'static Lifetime Promotion in Deref
A soundness bug in buffa's OwnedView<V> 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. Because these references appeared to be 'static, the borrow checker permitted them to outlive the OwnedView; once the OwnedView was dropped and its backing buffer freed, those references became dangling, enabling memory corruption, information disclosure of freed heap contents, and cross-thread misuse — all without any unsafe code in the calling application. Users are advised to update to the latest patched version of buffa.
Thank you to hackerone.com/suul for reporting this issue.
- Record
GHSA-9pwq-gcrx-wghh- CVSS 4.0
- 5.9 Medium
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 - Weakness
- CWE-200, CWE-416
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
buffacrates.io |
before 0.7.0 | 0.7.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-55406 is a medium vulnerability (CVSS 5.9) in Anthropics Buffa, published July 16, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.19%, the 9th percentile. Fixed in buffa 0.7.0.
References
github.com/anthropics/buffa/security/advisories/GHSA-9pwq-gcrx-wghh
github.com/anthropics/buffa/pull/154
github.com/anthropics/buffa/commit/7dcf50a1a40eca6ed8d6c6dd59f4310aa0d68b0e
github.com/anthropics/buffa/releases/tag/v0.7.0
nvd.nist.gov/vuln/detail/CVE-2026-55406
github.com/advisories/GHSA-9pwq-gcrx-wghh
github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55406.json
github.com/anthropics/buffa