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CVE-2026-81002
xdp: fix zero-copy frame layout
Published 2026-09-11 (37 days ago) by the Linux kernel CNA. Subsystem net/core. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-81002 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
xdp_convert_zc_to_xdp_frame() clones an XSK packet into an order-0 page and advertises PAGE_SIZE as its frame size. It allows the copied frame to occupy the page tail needed by skb_shared_info and records zero headroom even when metadata separates the frame header from packet data. An AF_XDP zero-copy packet redirected through cpumap can therefore make the skb overlap skb_shared_info or place it beyond the allocated page. Limit the copied layout to SKB_WITH_OVERHEAD(PAGE_SIZE) and include the metadata length in frame headroom. Redirect callers already handle a NULL conversion result. BUG: KASAN: slab-out-of-bounds in skb_gro_receive Write of size 4 at addr ffff88800cf37004 by task cpumap/1/map:1/146 Call Trace: skb_gro_receive (net/core/gro.c:174) udp_gro_receive (net/ipv4/udp_offload.c:812) inet_gro_receive (net/ipv4/af_inet.c:1539) dev_gro_receive (net/core/gro.c:515) gro_receive_skb (net/core/gro.c:633) cpu_map_kthread_run (kernel/bpf/cpumap.c:395) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:164) ret_from_fork_asm (arch/x86/entry/entry_64.S:255) Kernel panic - not syncing: KASAN: panic_on_warn set ...
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/core/xdp.c
- What this is
- XDP (eXpress Data Path)MAINTAINERS section matched on net/core/xdp.c · netdev@vger.kernel.org · Supported
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sid, bookworm · linux-6.12y
- y
- built into the kernel image on every flavour - only a patch removes it
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS Debian linux-config packages
Signals
- Published
- 2026-09-11 (37 days ago)source
- CVSS
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.51%, higher than 42.5% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/core
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.20 | 5.10.270 | dcb6db9ca651 |
| 4.20 | 5.15.221 | 220927301290 |
| 4.20 | 6.1.188 | ced3e18cd9b9 |
| 4.20 | 6.6.157 | 6de17275b3cc |
| 4.20 | 6.12.109 | 444216dacdbe |
| 4.20 | 6.18.50 | 15d1f3c0dbe7 |
| 4.20 | 7.2.4 | 68d7cc551223 |
| 4.20 | 7.3 | 71283aaa6c65 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- Received AF_XDP zero-copy packets reach xdp_convert_zc_to_xdp_frame() on XDP_REDIRECT into cpumap or a veth. On an internet-facing NIC with that hybrid XDP/AF_XDP setup, unauthenticated remote frames drive the cloned page into skb/GRO; AF_XDP bind is a victim-side prerequisite, not a local-only syscall bug.
- AC:LAttack complexity, low
- The sender chooses packet length, so a 4K UMEM/jumbo frame makes the clone occupy the skb_shared_info tail, and normal cpumap/veth metadata (bpf_xdp_adjust_meta) misplaces sinfo past the page. Either layout is attacker-reproducible with no race or uninfluenced memory-layout dependency.
- PR:NPrivileges required, none
- The remote sender needs no account or capability. CAP_NET_RAW, CAP_NET_ADMIN, and CAP_BPF are required only by the victim process that binds the XSK queue and loads the XDP redirect program, matching other AF_XDP RX-path kernel scores.
- UI:NUser interaction, none
- After the interface is configured, inbound packets are converted and passed to GRO automatically in NAPI or the cpumap kthread; no victim mount, click, or other per-packet action is required.
- S:UScope, unchanged
- The out-of-bounds skb_shared_info write corrupts host kernel heap/page memory in the same kernel authority. It is ordinary kernel memory corruption, not a VM, IOMMU, or sandbox boundary crossing.
- C:HConfidentiality impact, high
- skb_shared_info is placed past the order-0 page or overlapped with the copied frame, so GRO and build_skb write into adjacent objects that hold kernel pointers; that corruption can be turned into an arbitrary kernel read, so confidentiality is High.
- I:HIntegrity impact, high
- KASAN records a 4-byte out-of-bounds write in skb_gro_receive while building the skb around the mis-sized ZC clone. An OOB write of skb_shared_info (including pointer fields) is an arbitrary-write/control-flow primitive, so integrity is High.
- A:HAvailability impact, high
- The same GRO path panics under KASAN and oopses without it when skb_shared_info is written off the allocated page, so a remote packet can crash the kernel.