CVE-2026-64577 gtp: check skb_pull_data() return in gtp1u_send_echo_resp()
A missing return value check in the Linux kernel GTP module allows remote attackers to cause a kernel panic via crafted UDP packets.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64577?
CVE-2026-64577 is a high-severity vulnerability in Linux, published on 5 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
gtp: check skb_pull_data() return in gtp1u_send_echo_resp()
gtp1u_send_echo_resp() ignores skb_pull_data()'s return value. Its caller gtp1u_udp_encap_recv() only guarantees 16 bytes (udphdr + gtp1_header), but the pull requests 20 (gtp1_header_long + udphdr). For a 16-19 byte echo request the pull fails and returns NULL without advancing skb->data; execution continues, and the following skb_push() plus the IP header pushed by iptunnel_xmit() move skb->data below skb->head, tripping skb_under_panic().
Fix it by dropping the packet when skb_pull_data() fails.
skbuff: skb_under_panic: ... kernel BUG at net/core/skbuff.c:214! Call Trace: skb_push (net/core/skbuff.c:2648) iptunnel_xmit (net/ipv4/ip_tunnel_core.c:82) gtp_encap_recv (drivers/net/gtp.c:701 drivers/net/gtp.c:808 drivers/net/gtp.c:920) udp_queue_rcv_one_skb (net/ipv4/udp.c:2388) ... Kernel panic - not syncing: Fatal exception in interrupt
Which versions are affected by CVE-2026-64577?
How do I fix CVE-2026-64577?
Apply the vendor's patch.
Is CVE-2026-64577 being exploited?
There is no known exploitation of CVE-2026-64577 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-64577, DEBIAN-CVE-2026-64577, GHSA-cq6p-33cj-vghc, UBUNTU-CVE-2026-64577.