CVE-2021-29508
CRITICALCVE-2021-29508 is a critical-severity (CVSS 9.1) Deserialization of Untrusted Data vulnerability in Wire. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether CVE-2021-29508 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Insecure deserialization in Wire
Real-World Exposure
WireReal-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
Due to how Wire handles type information in its serialization format, malicious payloads can be passed to a deserializer. e.g. using a surrogate on the sender end, an attacker can pass information about a different type for the receiving end. And by doing so allowing the serializer to create any type on the deserializing end.
This is the same issue that exists for .NET BinaryFormatter https://docs.microsoft.com/en-us/visualstudio/code-quality/ca2300?view=vs-2019
This also applies to the fork of Wire, AkkaDotNet/Hyperion.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Wire | all versions | No fix |
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 Wire. 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.
Remediation status
No patched version of Wire has shipped for CVE-2021-29508 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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 CVE-2021-29508 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 CVE-2021-29508. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2021-29508 in your dependencies?
O3 detects CVE-2021-29508 across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.