by Kastro
Paper/Archive/CVE-2026-63993

CVE-2026-63993

Linux Linux — vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()

EPSS 0.5%CVSS 9.8
critical.is priorityof 100
38
CVSS 9.8 (CNA)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 43.7.437 × 208.7No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 6b8bfce9d2f774d2c2243e0248e03efb99bba6c06b8bfce9d2f774d2c2243e0248e03efb99bba6c0CNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 9257f56ac47ef1976bcd056cf986a9988eeec67a9257f56ac47ef1976bcd056cf986a9988eeec67aCNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 8d435d68d71fb875876b722f4136caf74f2f48bd8d435d68d71fb875876b722f4136caf74f2f48bdCNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < dc3bfa050f873371e745bdf478b1f5b738e5733ddc3bfa050f873371e745bdf478b1f5b738e5733dCNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 609e63312c29aad18026a1d3222e123d4b6b0feb609e63312c29aad18026a1d3222e123d4b6b0febCNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 5303925e360527243b46a440a04667826bbc72b75303925e360527243b46a440a04667826bbc72b7CNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < a493efd4336cf19122ae0e4cbb3d31b32d70deeaa493efd4336cf19122ae0e4cbb3d31b32d70deeaCNA
Linux4cb47a8644cc9eb8ec81190a50e79e6530d0297f – < 7d9ef0cb271555d8cf39fefe6c981e1493b25ecf7d9ef0cb271555d8cf39fefe6c981e1493b25ecfCNA
Linux5.95.10.259CNA

Scores by source

Linux (CNA)9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refgit.kernel.org/stable/c/6b8bfce9d2f774d2c2243e0248e03efb99bba6c0refgit.kernel.org/stable/c/9257f56ac47ef1976bcd056cf986a9988eeec67arefgit.kernel.org/stable/c/8d435d68d71fb875876b722f4136caf74f2f48bdrefgit.kernel.org/stable/c/dc3bfa050f873371e745bdf478b1f5b738e5733drefgit.kernel.org/stable/c/609e63312c29aad18026a1d3222e123d4b6b0febrefgit.kernel.org/stable/c/5303925e360527243b46a440a04667826bbc72b7refgit.kernel.org/stable/c/a493efd4336cf19122ae0e4cbb3d31b32d70deearefgit.kernel.org/stable/c/7d9ef0cb271555d8cf39fefe6c981e1493b25ecf