# CVE-2026-98555: llc: fix skb UAF and leaks on llc_mac_hdr_init() failure

CVE-2026-98555 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-98555, released October 19, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-98555
- Priority: High
- CVSS: 7.5 (Moderate)
- EPSS: 0.0031
- 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-2026-98555

## Description

In the Linux kernel, the following vulnerability has been resolved:  llc: fix skb UAF and leaks on llc_mac_hdr_init() failure  In llc_conn_ac_resend_i_xxx_x_set_0_or_send_rr(), if llc_mac_hdr_init() fails, kfree_skb(skb) is called instead of kfree_skb(nskb). This leaks the newly allocated nskb, reads from the freed skb via LLC_I_GET_NR(pdu), and double-frees skb when llc_conn_state_process() drops its reference.  In llc_sap_action_send_xid_r() and llc_sap_action_send_test_r(), nskb is leaked if llc_mac_hdr_init() returns an error.  Free nskb in all three error paths.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.190-1 | [DEBIAN-CVE-2026-98555](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98555.md) | Oct 19, 2026 |
| Linux | linux Debian 13.5 (trixie) | 6.12.113-1 | [DEBIAN-CVE-2026-98555](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98555.md) | Oct 19, 2026 |
| Linux | linux Debian 14 | 7.2.9-1 | [DEBIAN-CVE-2026-98555](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98555.md) | Oct 19, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.113-1~deb12u1 | [DEBIAN-CVE-2026-98555](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98555.md) | Oct 19, 2026 |

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Data as of 2026-11-08T19:12:23Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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