Bug 2517044 (CVE-2026-74559)

Summary: CVE-2026-74559 kernel: xsk: drain continuation descs after overflow in xsk_build_skb()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's AF_XDP (eXpress Data Path) networking component. This vulnerability, located in the `xsk_build_skb()` function, involves improper handling of network packet descriptors. When processing large or malformed multi-buffer packets, the system fails to properly drain continuation descriptors after an overflow, leading to their silent loss. An attacker could exploit this issue by sending specially crafted packets, resulting in a denial of service that impacts network communication.
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Description OSIDB Bzimport 2026-08-15 12:46:28 UTC 
In the Linux kernel, the following vulnerability has been resolved:

xsk: drain continuation descs after overflow in xsk_build_skb()

Fix generic xmit path multi-buffer logic when packets are either too big
(count of descriptors exceed MAX_SKB_FRAGS) or an invalid descriptor is
included in fragmented packet. Introduce xdp_sock::drain_cont and act
upon this flag - when it is set, keep on consuming descriptors from
AF_XDP Tx ring and put them directly onto Cq. Previously these
descriptors were silently lost and could never be reached again.
Comment 1 Mauro Matteo Cascella 2026-08-19 18:06:09 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081552-CVE-2026-74559-0b2d@gregkh/T