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CVE-2026-43254

· Published 06/05/2026 12:16 · Modified 06/05/2026 13:07

Labels: CVE-2026-43254 2026-05-06416baaa9-dc9f-4396-8d5f-8c081fb06d67CVE-2026-43254

Essential information

Published
06/05/2026 12:16
Modified
06/05/2026 13:07
Author
Creator
CISA KEV
No
CWE

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%.

NVD status

Status
Awaiting Analysis — CVE has been marked for Analysis. Normally once in this state the CVE will be analyzed by NVD staff within 24 hours.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD
View on NVD

Affected products (CPE)

ProductCPE
linux / kernel cpe:2.3:a:linux:kernel:*:*:*:*:*:*:*:*

References