Vulnerability in Kernel (CVE-2026-31517)
Summary
Vulnerability in Kernel (CVE-2026-31517). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.18.21, 6.19.11 or later.
Original description
The description as published by the source.
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:
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
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 enti…
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-31517 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.18.21, 6.19.11 or later.
If unsure, ask your IT team or search "Kernel CVE-2026-31517" on the vendor's site.
CVE-2026-31517 (Kernel)
Patched: 6.18.21, 6.19.11 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (unclassified) exists in Kernel.
Check the vendor advisory for the affected versions of Kernel.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 6.18.21, 6.19.11.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Kernel' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'Kernel' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
Kernelを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade Kernel to 6.18.21, 6.19.11ステージング環境で 6.18.21, 6.19.11 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-31517 linux-lts Fixed in: 6.18.35-r1
- Debian DEBIAN-CVE-2026-31517 linux Fixed in: 6.19.11-1
- Ubuntu UBUNTU-CVE-2026-31517 linux-hwe-edge
References
- advisory github.com
- advisory nvd.nist.gov
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org