# CVE-2026-43254: linux: In the Linux kernel, the following vulnerability has been resolved: ovpn: tcp - fix packet extraction from stream W... CVE-2026-43254 is fixed in 23 products on 1 platform, first by ALAS2023-2026-1702, released May 11, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-43254 - Priority: High - CVSS: 7.5 (high) - EPSS: 0.0045 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: May 6, 2026 ## 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%. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool6.18 amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | bpftool6.18-debuginfo amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel-livepatch-6.18.16-18.222 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18 amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-debuginfo amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-debuginfo-common-aarch64 amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-debuginfo-common-x86_64 amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-devel amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-headers amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-libbpf amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-libbpf-debuginfo amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-libbpf-devel amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-libbpf-static amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-modules-extra amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-modules-extra-common amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-tools amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-tools-debuginfo amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | kernel6.18-tools-devel amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | linux Debian 14 | 6.19.6-1 | [DEBIAN-CVE-2026-43254](https://patchblox.com/security/data/fix/linux/debian-cve-2026-43254.md) | May 15, 2026 | | Linux | perf6.18 amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | perf6.18-debuginfo amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | python3-perf6.18 amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | | Linux | python3-perf6.18-debuginfo amzn 2023 | 1:6.18.16-18.222.amzn2023 | [ALAS2023-2026-1702](https://patchblox.com/security/data/fix/linux/alas2023-2026-1702.md) | May 11, 2026 | --- Data as of 2026-11-09T01:18:40Z UTC. 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