CVE-2026-12707
HIGHSummary Cloudflare quiche was discovered to be vulnerable to memory resource exhaustion due to unbounded queuing of post-handshake client migration events. Impact quiche supports…
Description
Summary
Cloudflare quiche was discovered to be vulnerable to memory resource exhaustion due to unbounded queuing of post-handshake client migration events.
Impact
quiche supports the connection migration features described in Section 9 of RFC 9000, which allows a single QUIC connection to survive changes in the network path. Although quiche implements the protections described in Section 9.3 of RFC 9000 to limit server state commitment, it was discovered that the collection of PathEvents, intended to be consumed by applications via the path_event_next() function, was not bounded.
Once the QUIC handshake completed, a peer could exploit rapid source address migration in order to cause unbounded queuing of the PathEvent::ReusedSourceConnectionId type. Servers are vulnerable even if active connection migration is disabled.
Mitigation:
Applications can call path_event_next() to drain the PathEvent collection, mitigating the attack.
Users are requested to upgrade to quiche 0.29.3 which is the earliest version that prevents excessive queueing of PathEvent::ReusedSourceConnectionId.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. 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 the affected component has shipped for CVE-2026-12707 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-2026-12707 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-2026-12707. 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-2026-12707 in your dependencies?
O3 detects CVE-2026-12707 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.