CVE-2026-97953: Linux Vulnerability (CVSS 7)

Description

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: fix TX descriptor availability check for TSO traffic stmmac_tso_xmit() estimates the number of free TX descriptors required by a TSO skb as: (skb->len - proto_hdr_len) / TSO_MAX_BUFF_SIZE + 1 which assumes the payload is split into TSO_MAX_BUFF_SIZE chunks. This underestimates the descriptors actually consumed by stmmac_tso_allocator(), since each fragment is mapped individually and so it needs at least one descriptor regardless of its size. Moreover, one descriptor is used for the L2/L3/L4 headers and, when the MSS changes, one more is consumed for the MSS context descriptor. For a highly fragmented TSO skb the check can therefore pass even when the ring has too few free slots. stmmac_tso_allocator() then writes past the available descriptors, overwriting descriptors still owned by the DMA engine, corrupting the TX ring. Add stmmac_tso_get_num_desc() to compute the exact number of descriptors needed for the header, the linear payload and each fragment, plus the MSS context descriptor when required, and use it in the availability check.

Metrics

CVSS 3.1

7/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= f748be531d7012c456b97f66091d86b3675c5fef, < ffa6d2481bc1c87f822ecd626561484e4ee24cef; >= f748be531d7012c456b97f66091d86b3675c5fef, < c28175220f808c867d5618de8ecc6dbcc815c773; >= f748be531d7012c456b97f66091d86b3675c5fef, < 65820fc743eae322f7f94f6a64d07861211d4b21; >= f748be531d7012c456b97f66091d86b3675c5fef, < 5e38d732ec67a5b1f9a56e6c73add480c4b6030a
Linux	Linux	4.7

References

Timeline

Published: Sep 25, 2026
Last Modified: Sep 25, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-97953?

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: fix TX descriptor availability check for TSO traffic stmmac_tso_xmit() estimates the number of free TX descriptors required by a TSO skb as: (skb->len - proto_hdr_len) / TSO_MAX_BUFF_SIZE + 1 which assumes the payload is split into TSO_MAX_BUFF_SIZE chunks. This underestimates the descriptors actually consumed by stmmac_tso_allocator(), since each fragment is mapped individually and so it needs at least one descriptor regardless of its size. Moreover, one descriptor is used for the L2/L3/L4 headers and, when the MSS changes, one more is consumed for the MSS context descriptor. For a highly fragmented TSO skb the check can therefore pass even when the ring has too few free slots. stmmac_tso_allocator() then writes past the available descriptors, overwriting descriptors still owned by the DMA engine, corrupting the TX ring. Add stmmac_tso_get_num_desc() to compute the exact number of descriptors needed for the header, the linear payload and each fragment, plus the MSS context descriptor when required, and use it in the availability check.

How severe is CVE-2026-97953?

CVE-2026-97953 has a CVSS score of 7/10 (HIGH severity).

How do I fix CVE-2026-97953?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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