CVE-2025-64702
MEDIUMCVE-2025-64702 is a medium-severity (CVSS 5.3) CWE-770 vulnerability in github.com/quic-go/quic-go. O3 Security confirms whether CVE-2025-64702 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
quic-go HTTP/3 QPACK Header Expansion DoS
Blast Radius
github.com/quic-go/quic-goReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
quic-go is an implementation of the QUIC protocol in Go. Versions 0.56.0 and below are vulnerable to excessive memory allocation through quic-go's HTTP/3 client and server implementations by sending a QPACK-encoded HEADERS frame that decodes into a large header field section (many unique header names and/or large values). The implementation builds an http.Header (used on the http.Request and http.Response, respectively), while only enforcing limits on the size of the (QPACK-compressed) HEADERS frame, but not on the decoded header, leading to memory exhaustion. This issue is fixed in version 0.57.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/quic-go/quic-go | all versions | 0.57.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/quic-go/quic-go. 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 github.com/quic-go/quic-go to 0.57.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-64702 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 CVE-2025-64702 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-2025-64702. 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-2025-64702 in your dependencies?
O3 detects CVE-2025-64702 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.