Answer in brief
CVE-2026-63993 records a Critical severity (CVSS 9.8) vulnerability in vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <6b8bfce9d2f774d2c2243e0248e03efb99bba6c0 || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <9257f56ac47ef1976bcd056cf986a9988eeec67a || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <8d435d68d71fb875876b722f4136caf74f2f48bd || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <dc3bfa050f873371e745bdf478b1f5b738e5733d || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <609e63312c29aad18026a1d3222e123d4b6b0feb || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <5303925e360527243b46a440a04667826bbc72b7 || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <a493efd4336cf19122ae0e4cbb3d31b32d70deea || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <7d9ef0cb271555d8cf39fefe6c981e1493b25ecf | 6b8bfce9d2f774d2c2243e0248e03efb99bba6c0, 9257f56ac47ef1976bcd056cf986a9988eeec67a, 8d435d68d71fb875876b722f4136caf74f2f48bd, dc3bfa050f873371e745bdf478b1f5b738e5733d, 609e63312c29aad18026a1d3222e123d4b6b0feb, 5303925e360527243b46a440a04667826bbc72b7, a493efd4336cf19122ae0e4cbb3d31b32d70deea, 7d9ef0cb271555d8cf39fefe6c981e1493b25ecf |
| Linux/Linuxgeneric | 5.9 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
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.
Quoted source text, attributed separately from HOL analysis.