CVE-2026-72398
CVE-2026-72398 is a security vulnerability in Kernel. O3 Security confirms whether CVE-2026-72398 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
sctp: add INIT verification after cookie unpacking
Real-World Exposure
KernelReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Linux packages — download data is not available via public APIs for these ecosystems.
Description
In the Linux kernel, the following vulnerability has been resolved:
sctp: add INIT verification after cookie unpacking
In SCTP handshake, the INIT chunk is initially processed by the server and embedded into the cookie carried in INIT-ACK. The client then returns this cookie via COOKIE-ECHO, where the server unpacks it and reconstructs the original INIT chunk.
When cookie authentication is enabled, the cookie contents are protected against tampering, so reusing the unpacked INIT without re-verification is safe.
However, when cookie authentication is disabled, the reconstructed INIT can no longer be trusted. In this case, the INIT must be explicitly validated after unpacking to avoid processing potentially tampered data.
Add sctp_verify_init() checks after cookie unpacking in COOKIE-ECHO processing paths (sctp_sf_do_5_1D_ce() and sctp_sf_do_5_2_4_dupcook()) when cookie_auth_enable is disabled. On failure, the new association is freed and the packet is discarded.
Also tighten cookie validation in sctp_unpack_cookie() by verifying the embedded chunk type is SCTP_CID_INIT before treating it as an INIT chunk.
Finally, update sctp_verify_init() to validate parameter bounds using the actual embedded INIT length instead of chunk->chunk_end, since the INIT stored in COOKIE-ECHO may not span the entire chunk buffer.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐧Linux | Kernel | ≥ 2.6.12&&< 6.18.40 | 6.18.40 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Kernel. 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 Kernel to 6.18.40 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-72398 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-2026-72398 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-2026-72398. 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-2026-72398 in your dependencies?
O3 detects CVE-2026-72398 across Linux dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.