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CVE-2026-23300— net: ipv6: fix panic when IPv4 route references loopback IPv6 nexthop

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IPv4路由引用环回IPv6下一跳时分类错误，可能导致空指针取消引用和内核崩溃。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.13% · P2

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 493ced1ac47c48bb86d9d4e8e87df8592be85a0e< 607e68c1b7c5a30c795571be1906d716e989a644 affected
493ced1ac47c48bb86d9d4e8e87df8592be85a0e< c11d7c56c2076ee9cd72004f1976fe0734df2ae9 affected
493ced1ac47c48bb86d9d4e8e87df8592be85a0e< b5062fc2150614c9ea8a611c2e0cb6e047ebfa3a affected
493ced1ac47c48bb86d9d4e8e87df8592be85a0e< b299121e7453d23faddf464087dff513a495b4fc affected
493ced1ac47c48bb86d9d4e8e87df8592be85a0e< f7c9f8e3607440fe39300efbaf46cf7b5eecb23f affected
493ced1ac47c48bb86d9d4e8e87df8592be85a0e< b3b5a037d520afe3d5276e653bc0ff516bbda34c affected
493ced1ac47c48bb86d9d4e8e87df8592be85a0e< 8650db85b4259d2885d2a80fbc2317ce24194133 affected
493ced1ac47c48bb86d9d4e8e87df8592be85a0e< 21ec92774d1536f71bdc90b0e3d052eff99cf093 affected
… +10 more rows
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I. Basic Information for CVE-2026-23300

Vulnerability Information
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Vulnerability Title
net: ipv6: fix panic when IPv4 route references loopback IPv6 nexthop
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix panic when IPv4 route references loopback IPv6 nexthop When a standalone IPv6 nexthop object is created with a loopback device (e.g., "ip -6 nexthop add id 100 dev lo"), fib6_nh_init() misclassifies it as a reject route. This is because nexthop objects have no destination prefix (fc_dst=::), causing fib6_is_reject() to match any loopback nexthop. The reject path skips fib_nh_common_init(), leaving nhc_pcpu_rth_output unallocated. If an IPv4 route later references this nexthop, __mkroute_output() dereferences NULL nhc_pcpu_rth_output and panics. Simplify the check in fib6_nh_init() to only match explicit reject routes (RTF_REJECT) instead of using fib6_is_reject(). The loopback promotion heuristic in fib6_is_reject() is handled separately by ip6_route_info_create_nh(). After this change, the three cases behave as follows: 1. Explicit reject route ("ip -6 route add unreachable 2001:db8::/64"): RTF_REJECT is set, enters reject path, skips fib_nh_common_init(). No behavior change. 2. Implicit loopback reject route ("ip -6 route add 2001:db8::/32 dev lo"): RTF_REJECT is not set, takes normal path, fib_nh_common_init() is called. ip6_route_info_create_nh() still promotes it to reject afterward. nhc_pcpu_rth_output is allocated but unused, which is harmless. 3. Standalone nexthop object ("ip -6 nexthop add id 100 dev lo"): RTF_REJECT is not set, takes normal path, fib_nh_common_init() is called. nhc_pcpu_rth_output is properly allocated, fixing the crash when IPv4 routes reference this nexthop.
Source: CVE Program / CVE List V5
CVSS Information
N/A
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IPv4路由引用环回IPv6下一跳时分类错误，可能导致空指针取消引用和内核崩溃。
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 493ced1ac47c48bb86d9d4e8e87df8592be85a0e ~ 607e68c1b7c5a30c795571be1906d716e989a644 -
Linux Linux 5.3 -

II. Public POCs for CVE-2026-23300

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III. Intelligence Information for CVE-2026-23300

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Patches & Fixes for CVE-2026-23300 (6)

Same Patch Batch · Linux · 2026-03-25 · 116 CVEs total

CVE-2026-23395 8.8 HIGH Bluetooth: L2CAP: Fix accepting multiple L2CAP_ECRED_CONN_REQ
CVE-2026-31788 8.2 HIGH xen/privcmd: restrict usage in unprivileged domU
CVE-2026-23280 7.8 HIGH accel/amdxdna: Prevent ubuf size overflow
CVE-2026-23317 7.8 HIGH drm/vmwgfx: Return the correct value in vmw_translate_ptr functions
CVE-2026-23393 7.8 HIGH bridge: cfm: Fix race condition in peer_mep deletion
CVE-2026-23392 7.8 HIGH netfilter: nf_tables: release flowtable after rcu grace period on error
CVE-2026-23391 7.8 HIGH netfilter: xt_CT: drop pending enqueued packets on template removal
CVE-2026-23340 7.8 HIGH net: sched: avoid qdisc_reset_all_tx_gt() vs dequeue race for lockless qdiscs
CVE-2026-23372 7.8 HIGH nfc: rawsock: cancel tx_work before socket teardown
CVE-2026-23306 7.8 HIGH scsi: pm8001: Fix use-after-free in pm8001_queue_command()
CVE-2026-23288 7.8 HIGH accel/amdxdna: Fix out-of-bounds memset in command slot handling
CVE-2026-23378 7.8 HIGH net/sched: act_ife: Fix metalist update behavior
CVE-2026-23336 7.8 HIGH wifi: cfg80211: cancel rfkill_block work in wiphy_unregister()
CVE-2026-23351 7.8 HIGH netfilter: nft_set_pipapo: split gc into unlink and reclaim phase
CVE-2026-23383 7.8 HIGH bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing
CVE-2026-23350 7.8 HIGH drm/xe/queue: Call fini on exec queue creation fail
CVE-2026-23364 7.4 HIGH ksmbd: Compare MACs in constant time
CVE-2026-23294 7.0 HIGH bpf: Fix race in devmap on PREEMPT_RT
CVE-2026-23358 drm/amdgpu: Fix error handling in slot reset
CVE-2026-23357 can: mcp251x: fix deadlock in error path of mcp251x_open

Showing top 20 of 116 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23300

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