CVE-2026-63913
Linux netfilter conntrack flaw allows crafted RST to force TCP CLOSE.
Is CVE-2026-63913 being exploited?
Not confirmed. CVE-2026-63913 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.97% probability of exploitation in the next 30 days.
How severe is CVE-2026-63913?
CVE-2026-63913 is rated High with a CVSS score of 8.2. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-63913?
Yes. A fix has been recorded for CVE-2026-63913. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-63913 affect?
CVE-2026-63913 affects Linux kernel (netfilter/conntrack), Linux-based routers/firewalls, NAT gateways, Cloud hosts and containers using conntrack. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-63913?
Apply kernel updates; block/inspect unexpected RSTs at perimeter; monitor conntrack state and NAT timeouts.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attackers can send crafted RSTs with invalid sequence numbers to prematurely terminate NAT/tracked TCP connections, causing session disruption or DoS of networked services.
Patch when possible
- affected>= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 and < 2006979a15af5404bf932a325357683c0bac1656
- affected>= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 and < 6476c17d536dbd321c073242e762ddb2713a1238
- affected>= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 and < f5547bebc416d56f56fb5b86dc20aabfa42165a0
- affected>= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 and < 2bb6d82b586ea5a4cb73bbdd6b7432e96096bc77
- affected>= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 and < f206def4e86d810f927ba1d8e322ea72b29bce58
- affected>= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 and < b98ab51c45c5608a1c19ce7fd17a3032469bb83f
- affected>= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 and < d67c6adee8d1b65330d0174c4c367faba14e80a8
- affected>= 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 and < bed6e04be8e6b9133d8b16d5a42d0e0ce674fa9a
- affected2.6.15
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.