CVE-2024-26635

Name: CVE-2024-26635
Creator: NVD / NIST
Published: 2024-03-18T11:15:10.203+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.5/10EPSS 0.24%

Last modified Jun 17, 2026

CVE-2024-26635 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. In the Linux kernel, the following vulnerability has been resolved: llc: Drop support for ETH_P_TR_802_2. syzbot reported an uninit-value bug below. [0] llc supports ETH_P_802_2 (0x0004) and used to support ETH_P_TR_802_2 (0x0011), and syzbot abused the latter to trigger the bug. write$tun(r0, &(0x7f0000000040)={@val={0x0, 0x11}, @val, @mpls={[], @llc={@snap={0xaa, 0x1, ')', "90e5dd"}}}}, 0x16) llc_conn_handler() initialises local variables {saddr,daddr}.mac based on skb in llc_pdu_decode_sa()/llc_pdu_decode_da() and passes them to __llc_lookup(). However, the initialisation is done only when skb->protocol is htons(ETH_P_802_2), otherwise, __llc_lookup_established() and __llc_lookup_listener() will read garbage. The missing initialisation existed prior to commit 211ed865108e ("net: delete all instances of special processing for token ring"). It removed the part to kick out the token ring stuff but forgot to close the door allowing ETH_P_TR_802_2 packets to sneak into llc_rcv(). Let's remove llc_tr_packet_type and complete the deprecation. [0]: BUG: KMSAN: uninit-value in __llc_lookup_established+0xe9d/0xf90 __llc_lookup_established+0xe9d/0xf90 __llc_lookup net/llc/llc_conn.c:611 [inline] llc_conn_handler+0x4bd/0x1360 net/llc/llc_conn.c:791 llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206 __netif_receive_skb_one_core net/core/dev.c:5527 [inline] __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5641 netif_receive_skb_internal net/core/dev.c:5727 [inline] netif_receive_skb+0x58/0x660 net/core/dev.c:5786 tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1555 tun_get_user+0x53af/0x66d0 drivers/net/tun.c:2002 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048 call_write_iter include/linux/fs.h:2020 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x8ef/0x1490 fs/read_write.c:584 ksys_write+0x20f/0x4c0 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x93/0xd0 fs/read_write.c:646 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b Local variable daddr created at: llc_conn_handler+0x53/0x1360 net/llc/llc_conn.c:783 llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206 CPU: 1 PID: 5004 Comm: syz-executor994 Not tainted 6.6.0-syzkaller-14500-g1c41041124bd #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023. EPSS estimates a 0.24% chance of exploitation in the next 30 days.

Description

In the Linux kernel, the following vulnerability has been resolved: llc: Drop support for ETH_P_TR_802_2. syzbot reported an uninit-value bug below. [0] llc supports ETH_P_802_2 (0x0004) and used to support ETH_P_TR_802_2 (0x0011), and syzbot abused the latter to trigger the bug. write$tun(r0, &(0x7f0000000040)={@val={0x0, 0x11}, @val, @mpls={[], @llc={@snap={0xaa, 0x1, ')', "90e5dd"}}}}, 0x16) llc_conn_handler() initialises local variables {saddr,daddr}.mac based on skb in llc_pdu_decode_sa()/llc_pdu_decode_da() and passes them to __llc_lookup(). However, the initialisation is done only when skb->protocol is htons(ETH_P_802_2), otherwise, __llc_lookup_established() and __llc_lookup_listener() will read garbage. The missing initialisation existed prior to commit 211ed865108e ("net: delete all instances of special processing for token ring"). It removed the part to kick out the token ring stuff but forgot to close the door allowing ETH_P_TR_802_2 packets to sneak into llc_rcv(). Let's remove llc_tr_packet_type and complete the deprecation. [0]: BUG: KMSAN: uninit-value in __llc_lookup_established+0xe9d/0xf90 __llc_lookup_established+0xe9d/0xf90 __llc_lookup net/llc/llc_conn.c:611 [inline] llc_conn_handler+0x4bd/0x1360 net/llc/llc_conn.c:791 llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206 __netif_receive_skb_one_core net/core/dev.c:5527 [inline] __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5641 netif_receive_skb_internal net/core/dev.c:5727 [inline] netif_receive_skb+0x58/0x660 net/core/dev.c:5786 tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1555 tun_get_user+0x53af/0x66d0 drivers/net/tun.c:2002 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048 call_write_iter include/linux/fs.h:2020 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x8ef/0x1490 fs/read_write.c:584 ksys_write+0x20f/0x4c0 fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __x64_sys_write+0x93/0xd0 fs/read_write.c:646 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b Local variable daddr created at: llc_conn_handler+0x53/0x1360 net/llc/llc_conn.c:783 llc_rcv+0xfbb/0x14a0 net/llc/llc_input.c:206 CPU: 1 PID: 5004 Comm: syz-executor994 Not tainted 6.6.0-syzkaller-14500-g1c41041124bd #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023

Metrics

CVSS 3.1

5.5/10

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

EPSS Probability

0.24%

15.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-909

Affected Software

Vendor	Product	Versions	Update
Linux	Linux Kernel	>= 3.5, < 4.19.307	—
Linux	Linux Kernel	>= 4.20, < 5.4.269	—
Linux	Linux Kernel	>= 5.5, < 5.10.210	—
Linux	Linux Kernel	>= 5.11, < 5.15.149	—
Linux	Linux Kernel	>= 5.16, < 6.1.76	—
Linux	Linux Kernel	>= 6.2, < 6.6.15	—
Linux	Linux Kernel	>= 6.7, < 6.7.3	—
Linux	Linux Kernel	6.8	Rc1
Debian	Debian Linux	10.0	—

References

https://git.kernel.org/stable/c/165ad1e22779685c3ed3dd349c6c4c632309cc62Mailing List, Patch
https://git.kernel.org/stable/c/660c3053d992b68fee893a0e9ec9159228cffdc6Mailing List, Patch
https://git.kernel.org/stable/c/9ccdef19cf9497c2803b005369668feb91cacdfdMailing List, Patch
https://git.kernel.org/stable/c/b8e8838f82f332ae80c643dbb1ca4418d0628097Mailing List, Patch
https://git.kernel.org/stable/c/c0fe2fe7a5a291dfcf6dc64301732c8d3dc6a828Mailing List, Patch
https://git.kernel.org/stable/c/df57fc2f2abf548aa889a36ab0bdcc94a75399dcMailing List, Patch
https://git.kernel.org/stable/c/e3f9bed9bee261e3347131764e42aeedf1ffea61Mailing List, Patch
https://git.kernel.org/stable/c/f1f34a515fb1e25e85dee94f781e7869ae351fb8Mailing List, Patch
https://git.kernel.org/stable/c/165ad1e22779685c3ed3dd349c6c4c632309cc62Mailing List, Patch
https://git.kernel.org/stable/c/660c3053d992b68fee893a0e9ec9159228cffdc6Mailing List, Patch
https://git.kernel.org/stable/c/9ccdef19cf9497c2803b005369668feb91cacdfdMailing List, Patch
https://git.kernel.org/stable/c/b8e8838f82f332ae80c643dbb1ca4418d0628097Mailing List, Patch
https://git.kernel.org/stable/c/c0fe2fe7a5a291dfcf6dc64301732c8d3dc6a828Mailing List, Patch
https://git.kernel.org/stable/c/df57fc2f2abf548aa889a36ab0bdcc94a75399dcMailing List, Patch
https://git.kernel.org/stable/c/e3f9bed9bee261e3347131764e42aeedf1ffea61Mailing List, Patch
https://git.kernel.org/stable/c/f1f34a515fb1e25e85dee94f781e7869ae351fb8Mailing List, Patch
https://lists.debian.org/debian-lts-announce/2024/06/msg00017.htmlMailing List
https://lists.debian.org/debian-lts-announce/2024/06/msg00020.htmlMailing List

Timeline

Published: Mar 18, 2024
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2024-26635?

How severe is CVE-2024-26635?

CVE-2024-26635 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.24% probability of exploitation in the next 30 days.

How do I fix CVE-2024-26635?

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.

Are you affected by CVE-2024-26635?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST