Premature Release of Resource During Expected Lifetime Affecting kernel-rt-debug-kvm package, versions *
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-RHEL10-KERNELRTDEBUGKVM-21253209
- published20 Oct 2026
- disclosed18 Oct 2026
Introduced: 18 Oct 2026
NewCVE-2026-98503 (opens in a new tab)How to fix?
There is no fixed version for RHEL:10 kernel-rt-debug-kvm.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-rt-debug-kvm package and not the kernel-rt-debug-kvm package as distributed by RHEL.
See How to fix? for RHEL:10 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
packet: use ubuf_info completion for TX_RING packets
tpacket_snd sends skbs with frags pointing into its ring slots. Slots are released when skb->destructor is called.
A call to skb_orphan calls skb->destructor before the skb is freed. This can cause the slot to be reused while still linked into the skb.
Switch to standard zerocopy completion (ubuf_info) so the slot is only released once all references to the payload are freed or copied. Restore skb->destructor to standard sock_wfree.
The ubuf_info completion callback can be called with a NULL skb, but only from net_zcopy_put and related API, used by zerocopy implementations that hold their own reference on the uarg, such as MSG_ZEROCOPY. This uarg is only ever completed from skb_zcopy_clear, so skb is always set.
To prevent userspace from aliasing in-flight state on shared ring slots, allocate tpacket_uarg per packet, rather than per slot. This adds a small allocation to the transmit path. Use standard kmalloc to allow backporting to stable kernels.
The uarg holds an sk_wmem_alloc reference, rather than an sk_refcnt reference. packet_free_tx_ring waits on sk_wmem_alloc before freeing the ring pages. Always allocate vec->deferred for tx_ring so page-backed rings also wait on sk_wmem_alloc when skb_copy_ubufs drops page refs before calling tpacket_ubuf_complete.
Drop the tx_ring.pg_vec test that tpacket_destruct_skb performed before accessing the slot. The sk_wmem_alloc reference now guarantees that the slot is valid. The test is also not sufficient by itself, as it reads pg_vec without pg_vec_lock, so it can race with packet_set_ring.
As a result a slot is released when its payload is copied, which can be before transmission (e.g., in skb_orphan_frags_rx). If copied before skb_tx_timestamp() is called, no slot timestamp is recorded, similar to when skb_orphan() was called early in the datapath before this patch.
Revert the now unused previous skb_zcopy_.._nouarg infra.
Depends on commit 992cc9f94ca9 ("net/packet: defer vmalloc TX_RING free until skbs finish").
References
- https://bugzilla.redhat.com/show_bug.cgi?id=2554878
- https://access.redhat.com/security/cve/CVE-2026-98503
- https://git.kernel.org/stable/c/2a0c9afefc0ecea2cc30ccfbbbc98182a0986191
- https://git.kernel.org/stable/c/9518405613863d0bf0700927a21367f5942cf058
- https://git.kernel.org/stable/c/e67c455d79fbf709a94965f09a2be6bf4f4ba5fd
- https://git.kernel.org/stable/c/eda9bcb721f15a93746a99eabda33d80b86404fd