Integer Overflow or Wraparound The advisory has been revoked - it doesn't affect any version of package kernel6.18-libbpf-debuginfo (opens in a new tab)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-AMZN2023-KERNEL618LIBBPFDEBUGINFO-16740925
- published18 May 2026
- disclosed6 May 2026
Introduced: 6 May 2026
CVE-2026-43254 (opens in a new tab)Amendment
The Amazon-Linux security team deemed this advisory irrelevant for Amazon-Linux:2023.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel6.18-libbpf-debuginfo package and not the kernel6.18-libbpf-debuginfo package as distributed by Amazon-Linux.
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:
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.
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%.