# CVE-2026-31517: linux: In the Linux kernel, the following vulnerability has been resolved:  xfrm: iptfs: fix skb_put() panic on non-linear s...

CVE-2026-31517 is fixed in linux on 1 platform by DEBIAN-CVE-2026-31517 (version 6.19.11-1), released May 15, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-31517
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0012
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 22, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:  xfrm: iptfs: fix skb_put() panic on non-linear skb during reassembly  In iptfs_reassem_cont(), IP-TFS attempts to append data to the new inner packet 'newskb' that is being reassembled. First a zero-copy approach is tried if it succeeds then newskb becomes non-linear.  When a subsequent fragment in the same datagram does not meet the fast-path conditions, a memory copy is performed. It calls skb_put() to append the data and as newskb is non-linear it triggers SKB_LINEAR_ASSERT check.   Oops: invalid opcode: 0000 [#1] SMP NOPTI  [...]  RIP: 0010:skb_put+0x3c/0x40  [...]  Call Trace:   <IRQ>   iptfs_reassem_cont+0x1ab/0x5e0 [xfrm_iptfs]   iptfs_input_ordered+0x2af/0x380 [xfrm_iptfs]   iptfs_input+0x122/0x3e0 [xfrm_iptfs]   xfrm_input+0x91e/0x1a50   xfrm4_esp_rcv+0x3a/0x110   ip_protocol_deliver_rcu+0x1d7/0x1f0   ip_local_deliver_finish+0xbe/0x1e0   __netif_receive_skb_core.constprop.0+0xb56/0x1120   __netif_receive_skb_list_core+0x133/0x2b0   netif_receive_skb_list_internal+0x1ff/0x3f0   napi_complete_done+0x81/0x220   virtnet_poll+0x9d6/0x116e [virtio_net]   __napi_poll.constprop.0+0x2b/0x270   net_rx_action+0x162/0x360   handle_softirqs+0xdc/0x510   __irq_exit_rcu+0xe7/0x110   irq_exit_rcu+0xe/0x20   common_interrupt+0x85/0xa0   </IRQ>   <TASK>  Fix this by checking if the skb is non-linear. If it is, linearize it by calling skb_linearize(). As the initial allocation of newskb originally reserved enough tailroom for the entire reassembled packet we do not need to check if we have enough tailroom or extend it.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 6.19.11-1 | [DEBIAN-CVE-2026-31517](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31517.md) | May 15, 2026 |

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Data as of 2026-11-09T13:31:49Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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