Bug 2511415 (CVE-2026-64577)

Summary: CVE-2026-64577 kernel: gtp: check skb_pull_data() return in gtp1u_send_echo_resp()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's GPRS Tunnelling Protocol (GTP) module. This vulnerability occurs because the gtp1u_send_echo_resp() function does not properly check the return value when processing certain echo requests. A remote attacker could send a specially crafted echo request, causing the kernel to panic and leading to a Denial of Service (DoS) on the system.
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Description OSIDB Bzimport 2026-08-05 09:02:29 UTC 
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
Comment 1 gkamathe 2026-08-06 11:47:15 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026080524-CVE-2026-64577-0dfc@gregkh/T