CVE-2026-98255— tcp: exclude old ACKs from tcp fast 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.
在 Linux 内核中，已修复以下漏洞： TCP：在快速路径中排除旧的 ACK 包 在 TCP 快速路径处理中，排除那些序号在 SND.UNA 之前的旧 ACK 包，以及序号在 SND.NXT 之后的 ACK 包。 此类 ACK 包将被传递到慢速路径进行处理。在慢速路径中， 函数会根据 RFC 5961 规范以及提交 （“tcp：不接受从未发送过的字节的 ACK”）的要求，执行适当的验证和 Challenge ACK 处理。 这可以防止旧的 ACK 包在快速路径中、尚未进行适当 ACK 验证之前，被接受或修改连接状
Possible ATT&CK Techniques 1 AI
T1498.002 · Reflection AmplificationAffected Version Matrix 18
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Linux | Linux | 31770e34e43d6c8dee129bfee77e56c34e61f0e5< 07cacab90290f795bad2e566790f4ba8e84cdf5f |
affected |
31770e34e43d6c8dee129bfee77e56c34e61f0e5< 6eb9b697f50b73b9684e466c1e97f4ca8e947a59 |
affected | ||
31770e34e43d6c8dee129bfee77e56c34e61f0e5< b86e1e5a4bbcbbccde8b7a3d3486604b581f6628 |
affected | ||
31770e34e43d6c8dee129bfee77e56c34e61f0e5< 1c8448db5cf35a13d82b0c9004ffdb49358883e7 |
affected | ||
31770e34e43d6c8dee129bfee77e56c34e61f0e5< 8309dc2cc360056aa9cd2acfbfc25930798c3b66 |
affected | ||
31770e34e43d6c8dee129bfee77e56c34e61f0e5< ff037920c688ae6ca1153fec01e90e6782712455 |
affected | ||
31770e34e43d6c8dee129bfee77e56c34e61f0e5< 8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed |
affected | ||
31770e34e43d6c8dee129bfee77e56c34e61f0e5< f81e6c3fb06327bc49cdd6e559845293ba06a704 |
affected | ||
| … +10 more rows | |||
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I. Basic Information for CVE-2026-98255
Vulnerability Information
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Vulnerability Title
tcp: exclude old ACKs from tcp fast path
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
tcp: exclude old ACKs from tcp fast path
Exclude old ACKs before SND.UNA from the tcp fast path
as well as ACKs after SND.NXT.
Such ACKs will fall through to the slow path, where tcp_ack()
performs the appropriate validation and challenge ACK handling
according to RFC5961 and Commit 3d501dd326fb1c7 ("tcp: do not
accept ACK of bytes we never sent").
This prevents old ACKs from being accepted
or modifying connection state as part of the fast path before
appropriate ACK validation is applied.
In particular, this prevents payload carried by a segment with
an excessively old ACK from advancing RCV.NXT before the ACK
is rejected.
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
Affected Products
II. Public POCs for CVE-2026-98255
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POC
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Patches & Fixes for CVE-2026-98255 (8)
Same Patch Batch · Linux · 2026-10-06 · 208 CVEs total
| CVE-2026-98323 | 9.8 CRITICAL | RDMA/siw: Bound fragmented header copies by the remaining length |
| CVE-2026-98365 | 9.8 CRITICAL | RDMA/rxe: Fix integer overflow in mr_check_range() leading to OOB access |
| CVE-2026-98282 | 8.8 HIGH | powerpc/iommu: Fix the overflow validation in iommu_tce_check_ioba |
| CVE-2026-98283 | 8.8 HIGH | KVM: PPC: Book3S HV: fix use-after-free in kvmhv_emulate_tlbie_all_lpid() |
| CVE-2026-98339 | 8.8 HIGH | wifi: cfg80211: don't filter by BSS type when removing stale entries |
| CVE-2026-98171 | 8.8 HIGH | smb: client: fix next_buffer UAF and NextCommand bounds in compound PDUs |
| CVE-2026-98261 | 8.1 HIGH | cifs: Fix server use-after-free in cifs_chan_skip_or_disable() |
| CVE-2026-98357 | 8.1 HIGH | IB/isert: wait for deferred control PDU completions before releasing the connection |
| CVE-2026-98239 | 8.1 HIGH | net: lan743x: fix RX checksum use-after-free |
| CVE-2026-98341 | 7.8 HIGH | wifi: cfg80211: don't free driver-owned scan requests |
| CVE-2026-98324 | 7.8 HIGH | dmaengine: pxa: fix double counting of the hw descriptors |
| CVE-2026-98320 | 7.8 HIGH | netfilter: flowtable: hold reference on ct until flow is released |
| CVE-2026-98228 | 7.8 HIGH | mips: select CONFIG_WEAK_REORDERING_BEYOND_LLSC from CONFIG_EYEQ |
| CVE-2026-98229 | 7.8 HIGH | xfrm: save input state data before secpath resets |
| CVE-2026-98318 | 7.8 HIGH | smb: client: validate absolute native symlink targets before NT fixups |
| CVE-2026-98315 | 7.8 HIGH | ntfs: protect runlist updates with the runlist lock |
| CVE-2026-98260 | 7.8 HIGH | exec: Cleanup POSIX timers right after de_thread() |
| CVE-2026-98256 | 7.8 HIGH | signal: Prevent exec() race |
| CVE-2026-98258 | 7.8 HIGH | posix-cpu-timers: Prevent freeing a timer which is queued on the expiry list |
| CVE-2026-98254 | 7.8 HIGH | swiotlb: use the adjusted address for the highmem page lookup |
Showing top 20 of 208 CVEs. View all on vendor page → →
IV. Related Vulnerabilities
Same product: Linux
-
CVE-2026-98384
bpf: Fix out-of-bounds read of sk_protocol in bpf_sock_destr -
CVE-2026-98383
bpf: Disallow bpf_skb_pull_data() for LWT_SEG6LOCAL -
CVE-2026-98382
bpf: Reject dev-bound-only programs on other devices -
CVE-2026-98381
veth: manage XDP program pointers during channel resize -
CVE-2026-98380
net/sched: reject IDR error pointers when deleting actions
Same vendor: Linux
-
CVE-2026-98384
bpf: Fix out-of-bounds read of sk_protocol in bpf_sock_destr -
CVE-2026-98383
bpf: Disallow bpf_skb_pull_data() for LWT_SEG6LOCAL -
CVE-2026-98382
bpf: Reject dev-bound-only programs on other devices -
CVE-2026-98381
veth: manage XDP program pointers during channel resize -
CVE-2026-98380
net/sched: reject IDR error pointers when deleting actions
V. Comments for CVE-2026-98255
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