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CVE-2026-45905— xfrm: fix ip_rt_bug race in icmp_route_lookup reverse path

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ICMP路由查找中反向路径处理存在竞争条件，可能导致ip_rt_bug错误。

AI Predicted 5.5 Difficulty: Hard EPSS 0.11% · P1

Possible ATT&CK Techniques 1 AI

T1498 · Network Denial of Service

Affected Version Matrix 14

VendorProduct Version RangeStatus
Linux Linux 8b7817f3a959ed99d7443afc12f78a7e1fcc2063< 9a95ec9144eeff1fc6fbcc21b677e322c6f1430b affected
8b7817f3a959ed99d7443afc12f78a7e1fcc2063< 2c1f59005da9dd4b07b26984fd719e36557dc57c affected
8b7817f3a959ed99d7443afc12f78a7e1fcc2063< b04061f89ffc6168e7ec3c71d0086ec3c3797228 affected
8b7817f3a959ed99d7443afc12f78a7e1fcc2063< 1c9ef28f643cce34a6a6c36c8f4d6d60a60db7e1 affected
8b7817f3a959ed99d7443afc12f78a7e1fcc2063< 423ce12d10b426709489d6b84fdaa6d2f31c5652 affected
8b7817f3a959ed99d7443afc12f78a7e1fcc2063< 81b84de32bb27ae1ae2eb9acf0420e9d0d14bf00 affected
2.6.25 affected
< 2.6.25 unaffected
… +6 more rows
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I. Basic Information for CVE-2026-45905

Vulnerability Information
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Vulnerability Title
xfrm: fix ip_rt_bug race in icmp_route_lookup reverse path
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: xfrm: fix ip_rt_bug race in icmp_route_lookup reverse path icmp_route_lookup() performs multiple route lookups to find a suitable route for sending ICMP error messages, with special handling for XFRM (IPsec) policies. The lookup sequence is: 1. First, lookup output route for ICMP reply (dst = original src) 2. Pass through xfrm_lookup() for policy check 3. If blocked (-EPERM) or dst is not local, enter "reverse path" 4. In reverse path, call xfrm_decode_session_reverse() to get fl4_dec which reverses the original packet's flow (saddr<->daddr swapped) 5. If fl4_dec.saddr is local (we are the original destination), use __ip_route_output_key() for output route lookup 6. If fl4_dec.saddr is NOT local (we are a forwarding node), use ip_route_input() to simulate the reverse packet's input path 7. Finally, pass rt2 through xfrm_lookup() with XFRM_LOOKUP_ICMP flag The bug occurs in step 6: ip_route_input() is called with fl4_dec.daddr (original packet's source) as destination. If this address becomes local between the initial check and ip_route_input() call (e.g., due to concurrent "ip addr add"), ip_route_input() returns a LOCAL route with dst.output set to ip_rt_bug. This route is then used for ICMP output, causing dst_output() to call ip_rt_bug(), triggering a WARN_ON: ------------[ cut here ]------------ WARNING: net/ipv4/route.c:1275 at ip_rt_bug+0x21/0x30, CPU#1 Call Trace: <TASK> ip_push_pending_frames+0x202/0x240 icmp_push_reply+0x30d/0x430 __icmp_send+0x1149/0x24f0 ip_options_compile+0xa2/0xd0 ip_rcv_finish_core+0x829/0x1950 ip_rcv+0x2d7/0x420 __netif_receive_skb_one_core+0x185/0x1f0 netif_receive_skb+0x90/0x450 tun_get_user+0x3413/0x3fb0 tun_chr_write_iter+0xe4/0x220 ... Fix this by checking rt2->rt_type after ip_route_input(). If it's RTN_LOCAL, the route cannot be used for output, so treat it as an error. The reproducer requires kernel modification to widen the race window, making it unsuitable as a selftest. It is available at: https://gist.github.com/mrpre/eae853b72ac6a750f5d45d64ddac1e81
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ICMP路由查找中反向路径处理存在竞争条件，可能导致ip_rt_bug错误。
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 8b7817f3a959ed99d7443afc12f78a7e1fcc2063 ~ 9a95ec9144eeff1fc6fbcc21b677e322c6f1430b -
Linux Linux 2.6.25 -

II. Public POCs for CVE-2026-45905

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III. Intelligence Information for CVE-2026-45905

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Patches & Fixes for CVE-2026-45905 (5)

Other References for CVE-2026-45905 (1)

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

CVE-2026-46039 9.8 CRITICAL rxgk: Fix potential integer overflow in length check
CVE-2026-45898 9.8 CRITICAL RDMA/iwcm: Fix workqueue list corruption by removing work_list
CVE-2026-45988 9.8 CRITICAL rxrpc: Fix re-decryption of RESPONSE packets
CVE-2026-45972 9.8 CRITICAL smb: client: fix potential UAF and double free in smb2_open_file()
CVE-2026-46043 9.1 CRITICAL RDMA/rxe: Validate pad and ICRC before payload_size() in rxe_rcv
CVE-2026-45945 8.8 HIGH iommu/vt-d: Fix race condition during PASID entry replacement
CVE-2026-46056 8.8 HIGH Bluetooth: hci_event: fix potential UAF in SSP passkey handlers
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-2026-46099 8.1 HIGH net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels
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-2026-45910 7.8 HIGH RDMA/rxe: Fix race condition in QP timer handlers
CVE-2026-45862 7.8 HIGH iommu/vt-d: Flush cache for PASID table before using it
CVE-2026-45956 7.8 HIGH drm/exynos: vidi: use priv->vidi_dev for ctx lookup in vidi_connection_ioctl()
CVE-2026-46036 7.8 HIGH vfio/cdx: Serialize VFIO_DEVICE_SET_IRQS with a per-device mutex
CVE-2026-45942 7.8 HIGH ext4: fix e4b bitmap inconsistency reports
CVE-2026-45894 7.8 HIGH iommu/vt-d: Clear Present bit before tearing down PASID entry
CVE-2026-45933 7.8 HIGH bpf: Preserve id of register in sync_linked_regs()

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

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-45905

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