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CVE-2026-43254— ovpn: tcp - fix packet extraction from stream

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ovpn tcp驱动在从流中提取数据包时存在标头偏移溢出和协议标头未对齐问题，可能导致数据包丢失和性能下降。

CVSS 7.5 · High EPSS 0.61% · P48

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 11851cbd60ea1e5abbd97619d69845ead99303d6< 0315bec883c67fa1413c61e504a28dc5bd02eb37 affected
11851cbd60ea1e5abbd97619d69845ead99303d6< 7dba6cd7fb168d7615194a631c9c100c1c224131 affected
11851cbd60ea1e5abbd97619d69845ead99303d6< d4f687fbbce45b5e88438e89b5e26c0c15847992 affected
6.16 affected
< 6.16 unaffected
6.18.16≤ 6.18.* unaffected
6.19.6≤ 6.19.* unaffected
7.0≤ * unaffected
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I. Basic Information for CVE-2026-43254

Vulnerability Information
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Vulnerability Title
ovpn: tcp - fix packet extraction from stream
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ovpn: tcp - fix packet extraction from stream When processing TCP stream data in ovpn_tcp_recv, we receive large cloned skbs from __strp_rcv that may contain multiple coalesced packets. The current implementation has two bugs: 1. Header offset overflow: Using pskb_pull with large offsets on coalesced skbs causes skb->data - skb->head to exceed the u16 storage of skb->network_header. This causes skb_reset_network_header to fail on the inner decapsulated packet, resulting in packet drops. 2. Unaligned protocol headers: Extracting packets from arbitrary positions within the coalesced TCP stream provides no alignment guarantees for the packet data causing performance penalties on architectures without efficient unaligned access. Additionally, openvpn's 2-byte length prefix on TCP packets causes the subsequent 4-byte opcode and packet ID fields to be inherently misaligned. Fix both issues by allocating a new skb for each openvpn packet and using skb_copy_bits to extract only the packet content into the new buffer, skipping the 2-byte length prefix. Also, check the length before invoking the function that performs the allocation to avoid creating an invalid skb. If the packet has to be forwarded to userspace the 2-byte prefix can be pushed to the head safely, without misalignment. As a side effect, this approach also avoids the expensive linearization that pskb_pull triggers on cloned skbs with page fragments. In testing, this resulted in TCP throughput improvements of up to 74%.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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ovpn tcp驱动在从流中提取数据包时存在标头偏移溢出和协议标头未对齐问题，可能导致数据包丢失和性能下降。
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 11851cbd60ea1e5abbd97619d69845ead99303d6 ~ 0315bec883c67fa1413c61e504a28dc5bd02eb37 -
Linux Linux 6.16 -

II. Public POCs for CVE-2026-43254

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III. Intelligence Information for CVE-2026-43254

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Patches & Fixes for CVE-2026-43254 (3)

Same Patch Batch · Linux · 2026-05-06 · 224 CVEs total

CVE-2026-43186 9.8 CRITICAL ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()
CVE-2026-43185 9.8 CRITICAL ksmbd: fix signededness bug in smb_direct_prepare_negotiation()
CVE-2026-43125 9.8 CRITICAL dlm: validate length in dlm_search_rsb_tree
CVE-2026-43208 9.8 CRITICAL net: do not pass flow_id to set_rps_cpu()
CVE-2026-43198 9.8 CRITICAL tcp: fix potential race in tcp_v6_syn_recv_sock()
CVE-2026-43114 9.4 CRITICAL netfilter: nft_set_pipapo_avx2: don't return non-matching entry on expiry
CVE-2026-43117 9.1 CRITICAL btrfs: tracepoints: get correct superblock from dentry in event btrfs_sync_file()
CVE-2026-43083 9.1 CRITICAL net: ioam6: fix OOB and missing lock
CVE-2026-43197 9.1 CRITICAL netconsole: avoid OOB reads, msg is not nul-terminated
CVE-2026-43232 8.8 HIGH net: wan: farsync: Fix use-after-free bugs caused by unfinished tasklets
CVE-2026-43215 8.8 HIGH cifs: Fix locking usage for tcon fields
CVE-2026-43112 8.8 HIGH fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath
CVE-2026-43113 8.8 HIGH wifi: wl1251: validate packet IDs before indexing tx_frames
CVE-2026-43187 8.8 HIGH xfs: delete attr leaf freemap entries when empty
CVE-2026-43110 8.8 HIGH wifi: brcmfmac: validate bsscfg indices in IF events
CVE-2026-43283 8.8 HIGH net: ethernet: ec_bhf: Fix dma_free_coherent() dma handle
CVE-2026-43176 8.8 HIGH wifi: rtw89: pci: validate release report content before using for RTL8922DE
CVE-2026-43249 8.8 HIGH 9p/xen: protect xen_9pfs_front_free against concurrent calls
CVE-2026-43158 8.8 HIGH xfs: fix freemap adjustments when adding xattrs to leaf blocks
CVE-2026-43172 8.8 HIGH wifi: iwlwifi: fix 22000 series SMEM parsing

Showing top 20 of 224 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-43254

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