CVE-2025-21806net: let net.core.dev_weight always be non-zero
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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In the Linux kernel, the following vulnerability has been resolved: net: let net.core.dev_weight always be non-zero The following problem was encountered during stability test: (NULL net_device): NAPI poll function process_backlog+0x0/0x530 \ returned 1, exceeding its budget of 0. ------------[ cut here ]------------ list_add double add: new=ffff88905f746f48, prev=ffff88905f746f48, \ next=ffff88905f746e40. WARNING: CPU: 18 PID: 5462 at lib/list_debug.c:35 \ __list_add_valid_or_report+0xf3/0x130 CPU: 18 UID: 0 PID: 5462 Comm: ping Kdump: loaded Not tainted 6.13.0-rc7+ RIP: 0010:__list_add_valid_or_report+0xf3/0x130 Call Trace: ? __warn+0xcd/0x250 ? __list_add_valid_or_report+0xf3/0x130 enqueue_to_backlog+0x923/0x1070 netif_rx_internal+0x92/0x2b0 __netif_rx+0x15/0x170 loopback_xmit+0x2ef/0x450 dev_hard_start_xmit+0x103/0x490 __dev_queue_xmit+0xeac/0x1950 ip_finish_output2+0x6cc/0x1620 ip_output+0x161/0x270 ip_push_pending_frames+0x155/0x1a0 raw_sendmsg+0xe13/0x1550 __sys_sendto+0x3bf/0x4e0 __x64_sys_sendto+0xdc/0x1b0 do_syscall_64+0x5b/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e The reproduction command is as follows: sysctl -w net.core.dev_weight=0 ping 127.0.0.1 This is because when the napi's weight is set to 0, process_backlog() may return 0 and clear the NAPI_STATE_SCHED bit of napi->state, causing this napi to be re-polled in net_rx_action() until __do_softirq() times out. Since the NAPI_STATE_SCHED bit has been cleared, napi_schedule_rps() can be retriggered in enqueue_to_backlog(), causing this issue. Making the napi's weight always non-zero solves this problem. Triggering this issue requires system-wide admin (setting is not namespaced).
- CVSS
- 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 15, 2026
Affected products
Linux Linux linux:linux (from the name) | from e3876605450979fe52a1a03e7eb78a89bf59e76a before d0e0f9c8218826926d7692980c98236d9f21fd3c; from e3876605450979fe52a1a03e7eb78a89bf59e76a before c337c08819a4ec49edfdcd8fc46fbee120d8a5b2; from e3876605450979fe52a1a03e7eb78a89bf59e76a before 0e2f1d93d287d544d26f8ff293ea820a8079b9f8; from e3876605450979fe52a1a03e7eb78a89bf59e76a before 5860abbf15eeb61838b5e32e721ba67b0aa84450; from e3876605450979fe52a1a03e7eb78a89bf59e76a before 6ce38b5a6a49e65bad163162a54cb3f104c40b48; from e3876605450979fe52a1a03e7eb78a89bf59e76a before 33e2168788f8fb5cb8bd4f36cb1ef37d1d34dada; from e3876605450979fe52a1a03e7eb78a89bf59e76a before 1489824e5226a26841c70639ebd2d1aed390764b; from e3876605450979fe52a1a03e7eb78a89bf59e76a before d1f9f79fa2af8e3b45cffdeef66e05833480148a | CNA record |
Siemens SIMATIC S7-1500 TM MFP - BIOS siemens:simatic_s7_1500_tm_mfp_bios (from the name) | all versions | CISA ADP |
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name) | all versions | CISA ADP |
linux linux_kernel linux:linux_kernel | from 2.6.13 before 5.4.291; from 5.5 before 5.10.235; from 5.11 before 5.15.179; from 5.16 before 6.1.129; from 6.2 before 6.6.76; from 6.7 before 6.12.13; from 6.13 before 6.13.2; 2.6.12 | NVD |
References
- https://git.kernel.org/stable/c/d0e0f9c8218826926d7692980c98236d9f21fd3cpatch
- https://git.kernel.org/stable/c/c337c08819a4ec49edfdcd8fc46fbee120d8a5b2patch
- https://git.kernel.org/stable/c/0e2f1d93d287d544d26f8ff293ea820a8079b9f8patch
- https://git.kernel.org/stable/c/5860abbf15eeb61838b5e32e721ba67b0aa84450patch
- https://git.kernel.org/stable/c/6ce38b5a6a49e65bad163162a54cb3f104c40b48patch
- https://git.kernel.org/stable/c/33e2168788f8fb5cb8bd4f36cb1ef37d1d34dadapatch
- https://git.kernel.org/stable/c/1489824e5226a26841c70639ebd2d1aed390764bpatch
- https://git.kernel.org/stable/c/d1f9f79fa2af8e3b45cffdeef66e05833480148apatch
- https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
- https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
- https://cert-portal.siemens.com/productcert/html/ssa-265688.html
- https://cert-portal.siemens.com/productcert/html/ssa-503939.html
- https://cert-portal.siemens.com/productcert/html/ssa-784472.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.