Network-facing Linux kernel bug in netfilter bridge affects many distributions; can crash systems or enable kernel-level exploit, posing broad operational risk.
CVE-2026-64554
Use-after-free in Linux netfilter bridge IPv6 fragmentation enabling kernel crash or RCE
Is CVE-2026-64554 being exploited?
Not confirmed. CVE-2026-64554 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 0.26% probability of exploitation in the next 30 days.
How severe is CVE-2026-64554?
CVE-2026-64554 is rated High with a CVSS score of 8.8. 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-2026-64554?
Yes. A fix has been recorded for CVE-2026-64554. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-64554 affect?
CVE-2026-64554 affects Linux kernel (netfilter bridge / br_netfilter), IPv6 fragmentation functions (br_ip6_fragment, ip6_frag_next). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-64554?
Apply vendor/kernel updates now; block IPv6 fragmented packets on bridges as interim mitigation.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote crafted IPv6 fragments to bridged interfaces cause a use-after-free write, enabling kernel panic, crash, or possible remote kernel code execution/privilege escalation.
Immediate action required
- affected>= 764dd163ac922f8683b5bcd3007251ce7b26cd33 and < 8c10778ec674b67a07ea042fcba64270f3f38a5a
- affected>= 764dd163ac922f8683b5bcd3007251ce7b26cd33 and < 2731efa6364e47934c96eb69e01ea131e8af8030
- affected>= 764dd163ac922f8683b5bcd3007251ce7b26cd33 and < 00c06ef8c018493943891a7d0ca82b71b24f3180
- affected>= 764dd163ac922f8683b5bcd3007251ce7b26cd33 and < c141f69d0a0fb16964dbc293650047e69bda8af7
- affected>= 764dd163ac922f8683b5bcd3007251ce7b26cd33 and < f2e6596d10783557aeb9668da2a3b4d19deb2001
- affected>= 764dd163ac922f8683b5bcd3007251ce7b26cd33 and < 1c4f67c89fd27c4df4c70b135c2c59627698b3c0
- affected>= 764dd163ac922f8683b5bcd3007251ce7b26cd33 and < 4ac981a8b7ce7aec99a52d08f8a8953e8e120067
- affected>= 764dd163ac922f8683b5bcd3007251ce7b26cd33 and < 86f3ce81dd2b4b0aa2c3016c989a943e4b1b643d
- affected5.3
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.