CVE-2023-45814 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.
Tokens cached in the AuthenticationService are susceptible to reuse in Bunkum
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 CVE-2023-45814.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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 |
Affected Products
bunkumlittlebigfreshDetection & 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 CVE-2023-45814 is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.
Frequently Asked Questions
Is CVE-2023-45814 in your dependencies?
Find it across NuGet, including transitive dependencies.