Answer in brief
CVE-2025-21806 records a Unknown severity vulnerability in net: let net.core.dev_weight always be non-zero. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 TM MFP - BIOS (generic), Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystem (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 TM MFP - BIOS (generic), Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystem (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=e3876605450979fe52a1a03e7eb78a89bf59e76a <d0e0f9c8218826926d7692980c98236d9f21fd3c || >=e3876605450979fe52a1a03e7eb78a89bf59e76a <c337c08819a4ec49edfdcd8fc46fbee120d8a5b2 || >=e3876605450979fe52a1a03e7eb78a89bf59e76a <0e2f1d93d287d544d26f8ff293ea820a8079b9f8 || >=e3876605450979fe52a1a03e7eb78a89bf59e76a <5860abbf15eeb61838b5e32e721ba67b0aa84450 || >=e3876605450979fe52a1a03e7eb78a89bf59e76a <6ce38b5a6a49e65bad163162a54cb3f104c40b48 || >=e3876605450979fe52a1a03e7eb78a89bf59e76a <33e2168788f8fb5cb8bd4f36cb1ef37d1d34dada || >=e3876605450979fe52a1a03e7eb78a89bf59e76a <1489824e5226a26841c70639ebd2d1aed390764b || >=e3876605450979fe52a1a03e7eb78a89bf59e76a <d1f9f79fa2af8e3b45cffdeef66e05833480148a | d0e0f9c8218826926d7692980c98236d9f21fd3c, c337c08819a4ec49edfdcd8fc46fbee120d8a5b2, 0e2f1d93d287d544d26f8ff293ea820a8079b9f8, 5860abbf15eeb61838b5e32e721ba67b0aa84450, 6ce38b5a6a49e65bad163162a54cb3f104c40b48, 33e2168788f8fb5cb8bd4f36cb1ef37d1d34dada, 1489824e5226a26841c70639ebd2d1aed390764b, d1f9f79fa2af8e3b45cffdeef66e05833480148a |
| Linux/Linuxgeneric | 2.6.12 | Not reported |
| Siemens/SIMATIC S7-1500 TM MFP - BIOSgeneric | >=0 <* | * |
| Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystemgeneric | >=0 <* | * |
Published upstream
Feb 27, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 15, 2026
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).
Quoted source text, attributed separately from HOL analysis.