# CVE-2026-98798: net: bcmgenet: fix NULL dereference in set_coalesce before first open

CVE-2026-98798 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-98798, released October 19, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-98798
- Priority: Routine
- CVSS: 4.4 (Moderate)
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 18, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-98798

## Description

In the Linux kernel, the following vulnerability has been resolved:  net: bcmgenet: fix NULL dereference in set_coalesce before first open  The Rx ring priv and index are only set in bcmgenet_init_rx_ring(), which runs at open. Setting the Rx coalescing parameters on an interface that was never opened, e.g. "ethtool -C eth0 rx-usecs 50", dereferences a NULL ring->priv. The oops happens with RTNL held, so networking stays stuck until a reboot:    Unable to handle kernel paging request at virtual address 0000000000002788   pc : bcmgenet_set_rx_coalesce.isra.0+0x10/0x88   lr : bcmgenet_set_coalesce+0xe8/0x180   Call trace:    bcmgenet_set_rx_coalesce.isra.0+0x10/0x88 (P)    __ethnl_set_coalesce.isra.0+0x490/0x570    ethnl_set_coalesce+0x48/0xc0    ethnl_default_set_doit+0xf4/0x230    genl_family_rcv_msg_doit+0xe8/0x160    genl_rcv_msg+0x220/0x2a0    netlink_rcv_skb+0x68/0x140    genl_rcv+0x40/0x60    netlink_unicast+0x338/0x3c0    netlink_sendmsg+0x19c/0x3f8    __sock_sendmsg+0x64/0xc0    __sys_sendto+0x124/0x198    __arm64_sys_sendto+0x30/0x48  Set priv and index at probe. Writing the registers while the interface is down is harmless because open resets the MAC and bcmgenet_init_rx_coalesce() reapplies the stored values.  It was observed on a Raspberry Pi CM4, but should apply to all other genet devices.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.113-1 | [DEBIAN-CVE-2026-98798](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98798.md) | Oct 19, 2026 |
| Linux | linux Debian 14 | 7.2.10-1 | [DEBIAN-CVE-2026-98798](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98798.md) | Oct 19, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.113-1~deb12u1 | [DEBIAN-CVE-2026-98798](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98798.md) | Oct 19, 2026 |

---

Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.