GHSA-jrf2-h5j6-3rrq is a medium-severity (CVSS 5.3) CWE-772 vulnerability in Bunkum. A fix is available for Bunkum — see the affected versions and patch details below.
Bunkum tokens cached in the AuthenticationService are susceptible to a use-after-free
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-jrf2-h5j6-3rrq.
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-jrf2-h5j6-3rrq 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 378,567 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
BunkumReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Impact
First, a little bit of background. So, in the beginning, Bunkum's AuthenticationService only supported injecting IUsers. However, as Refresh and SoundShapesServer implemented permissions systems support for injecting ITokens into endpoints was added. All was well until 4.0.
Bunkum 4.0 then changed to enforce relations between ITokens and IUsers. This wasn't implemented in a very good way in the AuthenticationService, and ended up breaking caching in such a way that cached tokens would persist after the lifetime of the request - since we tried to cache both tokens and users. From that point until now, from what I understand, Bunkum was attempting to use that cached token at the start of the next request once cached.
Naturally, when that token expired, downstream projects like Refresh would remove the object from Realm - and cause the object in the cache to be in a detached state, causing an exception from invalid use of IToken.User. So in other words, a use-after-free since Realm can't manage the lifetime of the cached token.
Security-wise, the scope is fairly limited, can only be pulled off on a couple endpoints given a few conditions, and you can't guarantee which token you're going to get. Also, the token would get invalidated properly if the endpoint had either a IToken usage or a IUser usage. User interaction is required as authenticated requests must be performed.
Patches
The fix is to just wipe the token cache after the request was handled, which is now in 4.2.1. I'd recommend that you update. Unfortunately, there are no real workarounds for other versions in the 4.X.X range.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Bunkum | ≥ 4.0.0&&< 4.2.1 | 4.2.1dotnet add package Bunkum --version 4.2.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Bunkum, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Bunkum to 4.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jrf2-h5j6-3rrq 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-jrf2-h5j6-3rrq can be triaged on real exposure rather than presence alone.
Tailored to GHSA-jrf2-h5j6-3rrq. 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-jrf2-h5j6-3rrq in your dependencies?
O3 Security finds GHSA-jrf2-h5j6-3rrq across NuGet dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.