GHSA-87mf-9wg6-ppf8 — ouroboros
GHSA-87mf-9wg6-ppf8 is a security vulnerability in ouroboros. A fix is available for ouroboros — see the affected versions and patch details below.
Ouroboros is Unsound
Real-World Exposure
ouroborosReal-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
In 0.15.0 and prior, Ouroboros works internally by creating a struct where all uses of 'this are replaced by 'static. However, a recent addition to Miri checks that references passed to functions are valid during the entire execution of the function, even when those references are passed inside a struct. This poses an issue for dropping self-referencing values, as the reference becomes invalid during the dropping process. Effectively, since self-referencing structs are not allowed in vanilla Rust, there is no allowance for dropping data during a function that has also been given a reference to that data. There's usually no way to pass a and &a to the same function.
A fix was attempted, where the struct would be turned in to a raw byte array and only transformed back into the underlying data type inside each function. This is allowable as a reference can be created and die over the body of a function, as long as the reference was created inside the function. However, this is also not sound if the original struct contains padding. There is no way to initialize padding bytes to a known value that Miri will accept, so when it is cast to an array some of the bytes contain uninitialized values. This is not acceptable (despite the fact that these bytes are never read) due to the potential for optimizations that may read from the uninitialized bytes. Besides which, this fix does not allow for template or constant parameters as there is no way to check the size of a templated type without giving specific, concrete values for the template parameters.
The final solution was to use this fix while wrapping the raw byte array in MaybeUninit<>.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | ouroboros | all versions | 0.16.0cargo update -p ouroboros --precise 0.16.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ouroboros, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ouroboros to 0.16.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-87mf-9wg6-ppf8 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-87mf-9wg6-ppf8 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-87mf-9wg6-ppf8. 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-87mf-9wg6-ppf8 in your dependencies?
O3 Security finds GHSA-87mf-9wg6-ppf8 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.