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CVE-2026-46099— net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels

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seg6和rpl lwtunnels在处理NOREF dst时未正确处理并发FIB查找，可能导致在PREEMPT_RT环境下释放底层pcpu_rt。

CVSS 8.1 · High EPSS 0.41% · P34

Possible ATT&CK Techniques 1 AI

T1211 · Exploitation for Stealth

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux af4a2209b1344939eaac11f269c261d347cbc3ee< 51fef5a7c4d160839199e941929456ba21ddf73c affected
af4a2209b1344939eaac11f269c261d347cbc3ee< b258b849a580285a1692e782ebc902b44c884a71 affected
af4a2209b1344939eaac11f269c261d347cbc3ee< 6bd17925bd6866027a6555db17905b9fc073d38d affected
af4a2209b1344939eaac11f269c261d347cbc3ee< 52f9db67f8f35f436366cf4980b4f0a2583d0ef0 affected
af4a2209b1344939eaac11f269c261d347cbc3ee< b778b6d095421619c331fd2d7751143cd5387103 affected
af4a2209b1344939eaac11f269c261d347cbc3ee< 9dd5481f960e337b81d7dfe429529495c1c481c0 affected
af4a2209b1344939eaac11f269c261d347cbc3ee< f9c52a6ba9780bd27e0bf4c044fd91c13c778b6e affected
4.12 affected
… +8 more rows
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I. Basic Information for CVE-2026-46099

Vulnerability Information
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Vulnerability Title
net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels seg6_input_core() and rpl_input() call ip6_route_input() which sets a NOREF dst on the skb, then pass it to dst_cache_set_ip6() invoking dst_hold() unconditionally. On PREEMPT_RT, ksoftirqd is preemptible and a higher-priority task can release the underlying pcpu_rt between the lookup and the caching through a concurrent FIB lookup on a shared nexthop. Simplified race sequence: ksoftirqd/X higher-prio task (same CPU X) ----------- -------------------------------- seg6_input_core(,skb)/rpl_input(skb) dst_cache_get() -> miss ip6_route_input(skb) -> ip6_pol_route(,skb,flags) [RT6_LOOKUP_F_DST_NOREF in flags] -> FIB lookup resolves fib6_nh [nhid=N route] -> rt6_make_pcpu_route() [creates pcpu_rt, refcount=1] pcpu_rt->sernum = fib6_sernum [fib6_sernum=W] -> cmpxchg(fib6_nh.rt6i_pcpu, NULL, pcpu_rt) [slot was empty, store succeeds] -> skb_dst_set_noref(skb, dst) [dst is pcpu_rt, refcount still 1] rt_genid_bump_ipv6() -> bumps fib6_sernum [fib6_sernum from W to Z] ip6_route_output() -> ip6_pol_route() -> FIB lookup resolves fib6_nh [nhid=N] -> rt6_get_pcpu_route() pcpu_rt->sernum != fib6_sernum [W <> Z, stale] -> prev = xchg(rt6i_pcpu, NULL) -> dst_release(prev) [prev is pcpu_rt, refcount 1->0, dead] dst = skb_dst(skb) [dst is the dead pcpu_rt] dst_cache_set_ip6(dst) -> dst_hold() on dead dst -> WARN / use-after-free For the race to occur, ksoftirqd must be preemptible (PREEMPT_RT without PREEMPT_RT_NEEDS_BH_LOCK) and a concurrent task must be able to release the pcpu_rt. Shared nexthop objects provide such a path, as two routes pointing to the same nhid share the same fib6_nh and its rt6i_pcpu entry. Fix seg6_input_core() and rpl_input() by calling skb_dst_force() after ip6_route_input() to force the NOREF dst into a refcounted one before caching. The output path is not affected as ip6_route_output() already returns a refcounted dst.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/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seg6和rpl lwtunnels在处理NOREF dst时未正确处理并发FIB查找，可能导致在PREEMPT_RT环境下释放底层pcpu_rt。
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 af4a2209b1344939eaac11f269c261d347cbc3ee ~ 51fef5a7c4d160839199e941929456ba21ddf73c -
Linux Linux 4.12 -

II. Public POCs for CVE-2026-46099

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III. Intelligence Information for CVE-2026-46099

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Patches & Fixes for CVE-2026-46099 (7)

Same Patch Batch · Linux · 2026-05-27 · 275 CVEs total

CVE-2026-45988 9.8 CRITICAL rxrpc: Fix re-decryption of RESPONSE packets
CVE-2026-45898 9.8 CRITICAL RDMA/iwcm: Fix workqueue list corruption by removing work_list
CVE-2026-45972 9.8 CRITICAL smb: client: fix potential UAF and double free in smb2_open_file()
CVE-2026-46039 9.8 CRITICAL rxgk: Fix potential integer overflow in length check
CVE-2026-46043 9.1 CRITICAL RDMA/rxe: Validate pad and ICRC before payload_size() in rxe_rcv
CVE-2026-46056 8.8 HIGH Bluetooth: hci_event: fix potential UAF in SSP passkey handlers
CVE-2026-45945 8.8 HIGH iommu/vt-d: Fix race condition during PASID entry replacement
CVE-2026-45843 8.2 HIGH slip: bound decode() reads against the compressed packet length
CVE-2025-71311 8.2 HIGH fs/ntfs3: Initialize new folios before use
CVE-2026-46037 8.2 HIGH ipv4: icmp: validate reply type before using icmp_pointers
CVE-2026-46010 8.1 HIGH rxrpc: Fix error handling in rxgk_extract_token()
CVE-2026-46076 7.9 HIGH KVM: nSVM: Raise #UD if unhandled VMMCALL isn't intercepted by L1
CVE-2026-45951 7.8 HIGH bpf: Fix a potential use-after-free of BTF object
CVE-2026-45929 7.8 HIGH ovpn: fix possible use-after-free in ovpn_net_xmit
CVE-2026-46006 7.8 HIGH drm/nouveau: fix u32 overflow in pushbuf reloc bounds check
CVE-2026-46058 7.8 HIGH media: amphion: Fix race between m2m job_abort and device_run
CVE-2026-46062 7.8 HIGH ntfs3: fix integer overflow in run_unpack() volume boundary check
CVE-2026-45878 7.8 HIGH drm/amdkfd: Fix watch_id bounds checking in debug address watch v2
CVE-2026-45956 7.8 HIGH drm/exynos: vidi: use priv->vidi_dev for ctx lookup in vidi_connection_ioctl()
CVE-2026-45980 7.8 HIGH accel/amdxdna: Stop job scheduling across aie2_release_resource()

Showing top 20 of 275 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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