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CVE-2026-55406

Buffa: Use-After-Free in OwnedView via Unsound 'static Lifetime Promotion in Deref

5.9 MediumFix available

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

0.19%Up 0.1 points since Jul 17, 2026
90%50%10%1%

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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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 MediumCVSS: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

Affected packages
PackageAffectedFixed
buffa
crates.io
before 0.7.0
0.7.0

History

History
RecordedChangedSources
first indexedCVE 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

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