CVE-2025-39703

MEDIUM EPSS 4.4%
Published Sep 5, 20259mo ago · Modified Jun 17, 20261w ago
5.5 CVSS 3.1
Medium
Find Similar
Published Sep 5, 2025 9mo ago
Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: net, hsr: reject HSR frame if skb can't hold tag Receiving HSR frame with insufficient space to hold HSR tag in the skb can result in a crash (kernel BUG): [ 45.390915] skbuff: skb_under_panic: text:ffffffff86f32cac len:26 put:14 head:ffff888042418000 data:ffff888042417ff4 tail:0xe end:0x180 dev:bridge_slave_1 [ 45.392559] ------------[ cut here ]------------ [ 45.392912] kernel BUG at net/core/skbuff.c:211! [ 45.393276] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 45.393809] CPU: 1 UID: 0 PID: 2496 Comm: reproducer Not tainted 6.15.0 #12 PREEMPT(undef) [ 45.394433] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 45.395273] RIP: 0010:skb_panic+0x15b/0x1d0 <snip registers, remove unreliable trace> [ 45.402911] Call Trace: [ 45.403105] <IRQ> [ 45.404470] skb_push+0xcd/0xf0 [ 45.404726] br_dev_queue_push_xmit+0x7c/0x6c0 [ 45.406513] br_forward_finish+0x128/0x260 [ 45.408483] __br_forward+0x42d/0x590 [ 45.409464] maybe_deliver+0x2eb/0x420 [ 45.409763] br_flood+0x174/0x4a0 [ 45.410030] br_handle_frame_finish+0xc7c/0x1bc0 [ 45.411618] br_handle_frame+0xac3/0x1230 [ 45.413674] __netif_receive_skb_core.constprop.0+0x808/0x3df0 [ 45.422966] __netif_receive_skb_one_core+0xb4/0x1f0 [ 45.424478] __netif_receive_skb+0x22/0x170 [ 45.424806] process_backlog+0x242/0x6d0 [ 45.425116] __napi_poll+0xbb/0x630 [ 45.425394] net_rx_action+0x4d1/0xcc0 [ 45.427613] handle_softirqs+0x1a4/0x580 [ 45.427926] do_softirq+0x74/0x90 [ 45.428196] </IRQ> This issue was found by syzkaller. The panic happens in br_dev_queue_push_xmit() once it receives a corrupted skb with ETH header already pushed in linear data. When it attempts the skb_push() call, there's not enough headroom and skb_push() panics. The corrupted skb is put on the queue by HSR layer, which makes a sequence of unintended transformations when it receives a specific corrupted HSR frame (with incomplete TAG). Fix it by dropping and consuming frames that are not long enough to contain both ethernet and hsr headers. Alternative fix would be to check for enough headroom before skb_push() in br_dev_queue_push_xmit(). In the reproducer, this is injected via AF_PACKET, but I don't easily see why it couldn't be sent over the wire from adjacent network. Further Details: In the reproducer, the following network interface chain is set up: ┌────────────────┐ ┌────────────────┐ │ veth0_to_hsr ├───┤ hsr_slave0 ┼───┐ └────────────────┘ └────────────────┘ │ │ ┌──────┐ ├─┤ hsr0 ├───┐ │ └──────┘ │ ┌────────────────┐ ┌────────────────┐ │ │┌────────┐ │ veth1_to_hsr ┼───┤ hsr_slave1 ├───┘ └┤ │ └────────────────┘ └────────────────┘ ┌┼ bridge │ ││ │ │└────────┘ │ ┌───────┐ │ │ ... ├──────┘ └───────┘ To trigger the events leading up to crash, reproducer sends a corrupted HSR fr ---truncated---

CVSS Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
4.4% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-476 NULL Pointer Dereference Memory Safety

Affected Products 15

VendorProductVersionRange
linuxlinux_kernel*≥5.10.42  –  <5.10.241
linuxlinux_kernel*≥5.12.9  –  <5.13
linuxlinux_kernel*≥5.13.1  –  <5.15.190
linuxlinux_kernel*≥5.16  –  <6.1.149
linuxlinux_kernel*≥6.2  –  <6.6.103
linuxlinux_kernel*≥6.7  –  <6.12.44
linuxlinux_kernel*≥6.13  –  <6.16.4
linuxlinux_kernel5.13any
linuxlinux_kernel5.13any
linuxlinux_kernel5.13any
linuxlinux_kernel5.13any
linuxlinux_kernel5.13any
linuxlinux_kernel6.17any
linuxlinux_kernel6.17any
debiandebian_linux11.0any

References 10

  • cert-portal.siemens.com https://cert-portal.siemens.com/productcert/html/ssa-032379.html
  • git.kernel.org https://git.kernel.org/stable/c/3ae272ab523dd6bdc26e879027ed79feac9dd1b3
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/61009439e4bd8d74e705ee15940760321be91d8a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/7af76e9d18a9fd6f8611b3313c86c190f9b6a5a7
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/8d9bc4a375a1ba05f7dfa0407de8e510ab9bd14d
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/acd69b597bd3f76d3b3d322b84082226c00eeaa4
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b117c41b00902c1a7e24347c405cb82504aeae0b
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b640188b8a6690e685939053c7efdbc7818b5f4e
    Patch
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html
    Mailing ListThird Party Advisory
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
    Mailing ListThird Party Advisory

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/3ae272ab523dd6bdc26e879027ed79feac9dd1b3
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/61009439e4bd8d74e705ee15940760321be91d8a
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/7af76e9d18a9fd6f8611b3313c86c190f9b6a5a7
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/8d9bc4a375a1ba05f7dfa0407de8e510ab9bd14d
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/acd69b597bd3f76d3b3d322b84082226c00eeaa4
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b117c41b00902c1a7e24347c405cb82504aeae0b
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b640188b8a6690e685939053c7efdbc7818b5f4e
    Patch