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CVE-2026-80847— tcp: clamp route advmss to TCP_MIN_MSS

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基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于TCP对路由advmss值未正确限制，可能导致有效MSS降为零，进而在tcp_select_initial_window()中发生除零错误，造成拒绝服务。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.17% · P6

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< eaf4af9bd6975c2eff8d48820937c83032d968dc affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< cfb44c6028e6f979720315e0772bbd0d4d33ed61 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 6b8c20bf61924dfc38fefb145c9f7406d73fae53 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 31cf2349361902769dc323e4dbf4b449795ec288 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 870a9e42ecc6fe1b8c25d87af043cb0d9c178fe1 affected
2.6.12 affected
< 2.6.12 unaffected
6.12.111≤ 6.12.* unaffected
… +4 more rows
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I. Basic Information for CVE-2026-80847

Vulnerability Information
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Vulnerability Title
tcp: clamp route advmss to TCP_MIN_MSS
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: tcp: clamp route advmss to TCP_MIN_MSS tcp_select_initial_window() assumes that callers never pass an MSS smaller than 1, but route-derived advmss values can violate that assumption. A too-small explicit RTAX_ADVMSS is one way to get there, but it is not the only one. The same divide-by-zero can also be reached through the "default advmss" path when RTAX_ADVMSS is left at 0 and the effective advmss is later driven down by route MTU and min_adv_mss. Introduce a tcp_dst_advmss() helper that clamps route advmss to TCP_MIN_MSS before TCP consumes it, and use it in the TCP paths that derive advmss from dst metrics. This keeps the effective MSS from dropping to zero before tcp_select_initial_window() rounds the receive window.
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基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于TCP对路由advmss值未正确限制，可能导致有效MSS降为零，进而在tcp_select_initial_window()中发生除零错误，造成拒绝服务。
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 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 ~ eaf4af9bd6975c2eff8d48820937c83032d968dc -
Linux Linux 2.6.12 -

II. Public POCs for CVE-2026-80847

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III. Intelligence Information for CVE-2026-80847

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Patches & Fixes for CVE-2026-80847 (4)

Same Patch Batch · Linux · 2026-09-04 · 156 CVEs total

CVE-2026-80865 bpf: Add missing access_ok call to copy_user_syms
CVE-2026-80856 fuse: fix invalidate lock leak on setattr writeback failure
CVE-2026-80857 fuse: wait for FR_FINISHED on abort_on_kill to prevent use-after-free
CVE-2026-80858 fuse: publish io-uring queues with release semantics
CVE-2026-80859 fuse: fix missing barrier when checking io-uring readiness
CVE-2026-80860 fuse: fix race between interrupt and resend
CVE-2026-80861 usb: xhci: bail out of setup if the controller is inaccessible
CVE-2026-80862 nvme-tcp: fix usage of page_frag_cache
CVE-2026-80863 RDMA/rxe: Fix OOB in free_rd_atomic_resources()
CVE-2026-80864 RDMA/rxe: Fix responder UAF on IB_QP_MAX_DEST_RD_ATOMIC modify_qp
CVE-2026-80870 drm/amdkfd: Validate CRIU-restored IDs before idr_alloc
CVE-2026-80874 arm64: dts: renesas: ironhide: Describe inline ECC carveouts
CVE-2026-80873 KVM: arm64: nv: Write ESR_EL2 for injected nested SError exceptions
CVE-2026-80872 ALSA: hda/tas2781: Cancel async firmware request at unbind
CVE-2026-80871 crypto: xilinx-trng - Remove crypto_rng interface
CVE-2026-80868 ntfs3: Allocate iomap inline_data using alloc_page
CVE-2026-80866 tipc: avoid busy looping in tipc_exit_net()
CVE-2026-80867 alpha/PCI: Add security_locked_down() check to pci_mmap_resource()
CVE-2026-80855 fuse: fix invalidate lock leak on open O_TRUNC DAX failure
CVE-2026-80869 ntfs: bound the attribute-list entry in ntfs_read_inode_mount()

Showing top 20 of 156 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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