CVE-2026-63993
Linux Kernel use-after-free
- Published19 Jul 2026
Description
In the Linux kernel, the following vulnerability has been resolved: vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu() skb_tunnel_check_pmtu() can change skb->head. Reusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF. Use instead ip_hdr(skb) as done in drivers/net/bareudp.c and drivers/net/geneve.c. Found by Sashiko.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HAffected products
Remediation
- https://git.kernel.org/stable/c/5303925e360527243b46a440a04667826bbc72b7
- https://git.kernel.org/stable/c/609e63312c29aad18026a1d3222e123d4b6b0feb
- https://git.kernel.org/stable/c/6b8bfce9d2f774d2c2243e0248e03efb99bba6c0
- https://git.kernel.org/stable/c/7d9ef0cb271555d8cf39fefe6c981e1493b25ecf
- https://git.kernel.org/stable/c/8d435d68d71fb875876b722f4136caf74f2f48bd
- https://git.kernel.org/stable/c/9257f56ac47ef1976bcd056cf986a9988eeec67a
References
- https://git.kernel.org/stable/c/5303925e360527243b46a440a04667826bbc72b7
- https://git.kernel.org/stable/c/609e63312c29aad18026a1d3222e123d4b6b0feb
- https://git.kernel.org/stable/c/6b8bfce9d2f774d2c2243e0248e03efb99bba6c0
- https://git.kernel.org/stable/c/7d9ef0cb271555d8cf39fefe6c981e1493b25ecf
- https://git.kernel.org/stable/c/8d435d68d71fb875876b722f4136caf74f2f48bd
- https://git.kernel.org/stable/c/9257f56ac47ef1976bcd056cf986a9988eeec67a
- https://git.kernel.org/stable/c/a493efd4336cf19122ae0e4cbb3d31b32d70deea
- https://git.kernel.org/stable/c/dc3bfa050f873371e745bdf478b1f5b738e5733d
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2026-63993 being actively exploited?
CVE-2026-63993 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.51%.
How severe is CVE-2026-63993?
CVE-2026-63993 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.51% probability of exploitation.
Which products are affected by CVE-2026-63993?
Affected products include Linux Kernel.
How do I fix CVE-2026-63993?
Upgrade affected software to a fixed version, for example Linux Kernel 5.15.210 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2026-63993 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.