GHSA-px8v-pp82-rcvr
MEDIUMquic-go affected by an ICMP Packet Too Large Injection Attack on Linux
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
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
Impact
An off-path attacker can inject an ICMP Packet Too Large packet. Since affected quic-go versions used IP_PMTUDISC_DO, the kernel would then return a "message too large" error on sendmsg, i.e. when quic-go attempts to send a packet that exceeds the MTU claimed in that ICMP packet.
By setting this value to smaller than 1200 bytes (the minimum MTU for QUIC), the attacker can disrupt a QUIC connection. Crucially, this can be done after completion of the handshake, thereby circumventing any TCP fallback that might be implemented on the application layer (for example, many browsers fall back to HTTP over TCP if they're unable to establish a QUIC connection).
As far as I understand, the kernel tracks the MTU per 4-tuple, so the attacker needs to at least know the client's IP and port tuple to mount an attack (assuming that it knows the server's IP and port).
Patches
The fix is easy: Use IP_PMTUDISC_PROBE instead of IP_PMTUDISC_DO. This socket option only sets the DF bit, but disables the kernel's MTU tracking.
Has the problem been patched? What versions should users upgrade to?
Fixed in https://github.com/quic-go/quic-go/pull/4729 Released in https://github.com/quic-go/quic-go/releases/tag/v0.48.2
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
Use iptables to drop ICMP Unreachable packets.
References
Are there any links users can visit to find out more?
This bug was discovered while doing research for my new IETF draft on IP fragmentation: https://datatracker.ietf.org/doc/draft-seemann-tsvwg-udp-fragmentation/
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/quic-go/quic-go | all versions | 0.48.2 |
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 0.48.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-px8v-pp82-rcvr 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-px8v-pp82-rcvr 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-px8v-pp82-rcvr. 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-px8v-pp82-rcvr in your dependencies?
O3 detects GHSA-px8v-pp82-rcvr across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.