GHSA-xg8p-34w2-j49j is a high-severity (CVSS 8.4) Buffer Overflow vulnerability in linked_list_allocator. 1 public exploit reference exists, so weaponization risk is real. A fix is available for linked_list_allocator — see the affected versions and patch details below.
linked_list_allocator vulnerable to out-of-bound writes on `Heap` initialization and `Heap::extend`
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for GHSA-xg8p-34w2-j49j.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-xg8p-34w2-j49j plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 376,715 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
linked_list_allocatorReal-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
What kind of vulnerability is it? Who is impacted?
This vulnerability impacts all the initialization functions on the Heap and LockedHeap types, including Heap::new, Heap::init, Heap::init_from_slice, and LockedHeap::new. It also affects multiple uses of the Heap::extend method.
Initialization Functions
The heap initialization methods were missing a minimum size check for the given heap size argument. This could lead to out-of-bound writes when a heap was initialized with a size smaller than 3 * size_of::<usize> because of metadata write operations.
Heap::extend
This vulnerability impacts three specific uses of the Heap::extend method:
- When calling
Heap::extendwith a size smaller than twousizes (e.g., 16 onx86_64), the size was erroneously rounded up to the minimum size, which could result in an out-of-bounds write. - Calling
Heap::extendon an empty heap tried to construct a heap starting at address 0, which is also an out-of-bounds write.- One specific way to trigger this accidentally is to call
Heap::new(or a similar constructor) with a heap size that is smaller than twousizes. This was treated as an empty heap as well.
- One specific way to trigger this accidentally is to call
- Calling
Heap::extendon a heap whose size is not a multiple of the size of twousizes resulted in unaligned writes. It also left the heap in an unexpected state, which might lead to subsequent issues. We did not find a way to exploit this undefined behavior yet (apart from DoS on platforms that fault on unaligned writes).
Patches
Has the problem been patched? What versions should users upgrade to?
We published a patch in version 0.10.2 and recommend all users to upgrade to it. This patch release includes the following changes:
- The initialization functions now panic if the given size is not large enough to store the necessary metadata. Depending on the alignment of the heap bottom pointer, the minimum size is between
2 * size_of::<usize>and3 * size_of::<usize>. - The
extendmethod now panics when trying to extend an unitialized heap. - Extend calls with a size smaller than
size_of::<usize>() * 2are now buffered internally and not added to the list directly. The buffered region will be merged with futureextendcalls. - The
size()method now returns the usable size of the heap, which might be slightly smaller than thetop() - bottom()difference because of alignment constraints.
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
To avoid this issue, ensure that the heap is only initialized with a size larger than 3 * size_of::<usize> and that the Heap::extend method is only called with sizes larger than 2 * size_of::<usize>(). Also, ensure that the total heap size is (and stays) a multiple of 2 * size_of::<usize>().
For more information
If you have any questions or comments about this advisory:
- Open an issue in this repository
- Email @phil-opp at [email protected]
Acknowledgements
This issue was responsibly reported by Evan Richter at ForAllSecure and found with Mayhem and cargo fuzz.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | linked_list_allocator | all versions | 0.10.2cargo update -p linked_list_allocator --precise 0.10.2 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for linked_list_allocator, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update linked_list_allocator to 0.10.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xg8p-34w2-j49j 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-xg8p-34w2-j49j can be triaged on real exposure rather than presence alone.
Tailored to GHSA-xg8p-34w2-j49j. 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-xg8p-34w2-j49j in your dependencies?
O3 Security finds GHSA-xg8p-34w2-j49j across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.