CVE-2025-21806net: let net.core.dev_weight always be non-zero
- 5.5MediumCVSS base score
- 0.23%Exploitation in 30 daysEPSS · top 86% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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).
Timeline
ID reserved
By Linux
- 2 months later
· 2 months later
Published
- 20 months later
· 20 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.23% · top 86% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.
Affected products
- affected e3876605450979fe52a1a03e7eb78a89bf59e76a – < d0e0f9c8218826926d7692980c98236d9f21fd3c
- affected e3876605450979fe52a1a03e7eb78a89bf59e76a – < c337c08819a4ec49edfdcd8fc46fbee120d8a5b2
- affected e3876605450979fe52a1a03e7eb78a89bf59e76a – < 0e2f1d93d287d544d26f8ff293ea820a8079b9f8
- affected e3876605450979fe52a1a03e7eb78a89bf59e76a – < 5860abbf15eeb61838b5e32e721ba67b0aa84450
- affected e3876605450979fe52a1a03e7eb78a89bf59e76a – < 6ce38b5a6a49e65bad163162a54cb3f104c40b48
- affected e3876605450979fe52a1a03e7eb78a89bf59e76a – < 33e2168788f8fb5cb8bd4f36cb1ef37d1d34dada
- affected e3876605450979fe52a1a03e7eb78a89bf59e76a – < 1489824e5226a26841c70639ebd2d1aed390764b
- affected e3876605450979fe52a1a03e7eb78a89bf59e76a – < d1f9f79fa2af8e3b45cffdeef66e05833480148a
- affected 2.6.12
- unaffected < 2.6.12
- unaffected 5.4.291 – ≤ 5.4.*
- unaffected 5.10.235 – ≤ 5.10.*
- unaffected 5.15.179 – ≤ 5.15.*
- unaffected 6.1.129 – ≤ 6.1.*
- unaffected 6.6.76 – ≤ 6.6.*
- unaffected 6.12.13 – ≤ 6.12.*
- unaffected 6.13.2 – ≤ 6.13.*
- unaffected 6.14 – ≤ *
References
References13
- https://git.kernel.org/stable/c/d0e0f9c8218826926d7692980c98236d9f21fd3c (opens in a new tab)
- https://git.kernel.org/stable/c/c337c08819a4ec49edfdcd8fc46fbee120d8a5b2 (opens in a new tab)
- https://git.kernel.org/stable/c/0e2f1d93d287d544d26f8ff293ea820a8079b9f8 (opens in a new tab)
- https://git.kernel.org/stable/c/5860abbf15eeb61838b5e32e721ba67b0aa84450 (opens in a new tab)
- https://git.kernel.org/stable/c/6ce38b5a6a49e65bad163162a54cb3f104c40b48 (opens in a new tab)
- https://git.kernel.org/stable/c/33e2168788f8fb5cb8bd4f36cb1ef37d1d34dada (opens in a new tab)
- https://git.kernel.org/stable/c/1489824e5226a26841c70639ebd2d1aed390764b (opens in a new tab)
- https://git.kernel.org/stable/c/d1f9f79fa2af8e3b45cffdeef66e05833480148a (opens in a new tab)
- https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html (opens in a new tab)
- https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-265688.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-503939.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2025-5987 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2025-21806)Record last updated .