GHSA-fpf5-4jw8-67x8 is a high-severity (CVSS 7.5) remote code execution vulnerability in rust-zserio. A fix is available for rust-zserio — see the affected versions and patch details below.
rust-zserio has Unbounded Memory Allocation
Real-World Exposure
rust-zserioReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Impact
When deserializing arrays, strings or bytes (blob) types zserio first reads the size of the variable, and then allocates sufficient memory to load data. Since the size is always trusted this can be abused by creating a data file with a large size value, causing the zserio runtime to allocate large amounts of memory.
Patches
Please cherry-pick 57f5fb.
Workarounds
- Do not accept
zserio-encoded messages from non-trusted sources. - Allocate a maximum heap amount to
rust-zerioto avoid impacting other applications.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | rust-zserio | all versions | 0.5.4cargo update -p rust-zserio --precise 0.5.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rust-zserio, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rust-zserio to 0.5.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fpf5-4jw8-67x8 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-fpf5-4jw8-67x8 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-fpf5-4jw8-67x8. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-fpf5-4jw8-67x8 in your dependencies?
O3 Security finds GHSA-fpf5-4jw8-67x8 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.