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.
Blast Radius
PeterO.CborReal-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
Due to this library's use of an inefficient algorithm, it is vulnerable to a denial of service attack when a maliciously crafted input is passed to DecodeFromBytes or other CBOR decoding mechanisms in this library.
Affected versions include versions 4.0.0 through 4.5.0.
This vulnerability was privately reported to me.
Patches
This issue has been fixed in version 4.5.1. Users should use the latest version of this library. (The latest version is not necessarily 4.5.1. Check the NuGet page to see the latest version's version number.)
Workarounds
Again, users should use the latest version of this library.
In the meantime, note that the inputs affected by this issue are all CBOR maps or contain CBOR maps. An input that decodes to a single CBOR object is not capable of containing a CBOR map if—
- it begins with a byte other than 0x80 through 0xDF, or
- it does not contain a byte in the range 0xa0 through 0xBF.
Such an input is not affected by this vulnerability and an application can choose to perform this check before passing it to a CBOR decoding mechanism.
For more information
If you have any questions or comments about this advisory:
- Open an issue in the CBOR repository.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | PeterO.Cbor | ≥ 4.0.0&&< 4.5.1 | 4.5.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for PeterO.Cbor. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update PeterO.Cbor to 4.5.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-6r92-cgxc-r5fg 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 pinpoints whether GHSA-6r92-cgxc-r5fg is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-6r92-cgxc-r5fg. 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-6r92-cgxc-r5fg in your dependencies?
O3 detects GHSA-6r92-cgxc-r5fg across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.