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CVE-2025-21823— batman-adv: Drop unmanaged ELP metric worker

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于未管理的ELP度量工作项可能导致无效内存访问。

CVSS 7.8 · High EPSS 0.24% · P14

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux c833484e5f3872a38fe232c663586069d5ad9645< 1c334629176c2d644befc31a20d4bf75542f7631 affected
c833484e5f3872a38fe232c663586069d5ad9645< a0019971f340ae02ba54cf1861f72da7e03e6b66 affected
c833484e5f3872a38fe232c663586069d5ad9645< 3c0e0aecb78cb2a2ca1dc701982d08fedb088dc6 affected
c833484e5f3872a38fe232c663586069d5ad9645< 781a06fd265a8151f7601122d9c2e985663828ff affected
c833484e5f3872a38fe232c663586069d5ad9645< a7aa2317285806640c844acd4cd2cd768e395264 affected
c833484e5f3872a38fe232c663586069d5ad9645< 0fdc3c166ac17b26014313fa2b93696354511b24 affected
c833484e5f3872a38fe232c663586069d5ad9645< af264c2a9adc37f4bdf88ca7f3affa15d8c7de9e affected
c833484e5f3872a38fe232c663586069d5ad9645< 8c8ecc98f5c65947b0070a24bac11e12e47cc65d affected
… +10 more rows
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I. Basic Information for CVE-2025-21823

Vulnerability Information
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Vulnerability Title
batman-adv: Drop unmanaged ELP metric worker
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: batman-adv: Drop unmanaged ELP metric worker The ELP worker needs to calculate new metric values for all neighbors "reachable" over an interface. Some of the used metric sources require locks which might need to sleep. This sleep is incompatible with the RCU list iterator used for the recorded neighbors. The initial approach to work around of this problem was to queue another work item per neighbor and then run this in a new context. Even when this solved the RCU vs might_sleep() conflict, it has a major problems: Nothing was stopping the work item in case it is not needed anymore - for example because one of the related interfaces was removed or the batman-adv module was unloaded - resulting in potential invalid memory accesses. Directly canceling the metric worker also has various problems: * cancel_work_sync for a to-be-deactivated interface is called with rtnl_lock held. But the code in the ELP metric worker also tries to use rtnl_lock() - which will never return in this case. This also means that cancel_work_sync would never return because it is waiting for the worker to finish. * iterating over the neighbor list for the to-be-deactivated interface is currently done using the RCU specific methods. Which means that it is possible to miss items when iterating over it without the associated spinlock - a behaviour which is acceptable for a periodic metric check but not for a cleanup routine (which must "stop" all still running workers) The better approch is to get rid of the per interface neighbor metric worker and handle everything in the interface worker. The original problems are solved by: * creating a list of neighbors which require new metric information inside the RCU protected context, gathering the metric according to the new list outside the RCU protected context * only use rcu_trylock inside metric gathering code to avoid a deadlock when the cancel_delayed_work_sync is called in the interface removal code (which is called with the rtnl_lock held)
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于未管理的ELP度量工作项可能导致无效内存访问。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux c833484e5f3872a38fe232c663586069d5ad9645 ~ 1c334629176c2d644befc31a20d4bf75542f7631 -
Linux Linux 4.6 -

II. Public POCs for CVE-2025-21823

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III. Intelligence Information for CVE-2025-21823

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Patches & Fixes for CVE-2025-21823 (5)

Other References for CVE-2025-21823 (3)

Same Patch Batch · Linux · 2025-02-27 · 177 CVEs total

CVE-2025-21805 9.8 CRITICAL RDMA/rtrs: Add missing deinit() call
CVE-2025-21796 9.8 CRITICAL nfsd: clear acl_access/acl_default after releasing them
CVE-2025-21707 9.8 CRITICAL mptcp: consolidate suboption status
CVE-2025-21748 9.8 CRITICAL ksmbd: fix integer overflows on 32 bit systems
CVE-2024-58006 9.6 CRITICAL PCI: dwc: ep: Prevent changing BAR size/flags in pci_epc_set_bar()
CVE-2024-57999 8.8 HIGH powerpc/pseries/iommu: IOMMU incorrectly marks MMIO range in DDW
CVE-2025-21735 8.8 HIGH NFC: nci: Add bounds checking in nci_hci_create_pipe()
CVE-2024-57997 8.8 HIGH wifi: wcn36xx: fix channel survey memory allocation size
CVE-2024-57995 8.8 HIGH wifi: ath12k: fix read pointer after free in ath12k_mac_assign_vif_to_vdev()
CVE-2025-21710 8.2 HIGH tcp: correct handling of extreme memory squeeze
CVE-2025-21766 8.1 HIGH ipv4: use RCU protection in __ip_rt_update_pmtu()
CVE-2024-57973 8.1 HIGH rdma/cxgb4: Prevent potential integer overflow on 32bit
CVE-2025-21765 8.1 HIGH ipv6: use RCU protection in ip6_default_advmss()
CVE-2025-21760 8.1 HIGH ndisc: extend RCU protection in ndisc_send_skb()
CVE-2025-21762 8.1 HIGH arp: use RCU protection in arp_xmit()
CVE-2024-58010 7.8 HIGH binfmt_flat: Fix integer overflow bug on 32 bit systems
CVE-2024-58008 7.8 HIGH KEYS: trusted: dcp: fix improper sg use with CONFIG_VMAP_STACK=y
CVE-2025-21764 7.8 HIGH ndisc: use RCU protection in ndisc_alloc_skb()
CVE-2025-21791 7.8 HIGH vrf: use RCU protection in l3mdev_l3_out()
CVE-2025-21763 7.8 HIGH neighbour: use RCU protection in __neigh_notify()

Showing top 20 of 177 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-21823

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