high CVSS 7.8

CVE-2024-26782·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: mptcp: fix double-free on socket dismantle when MPTCP server accepts an incoming connection, it clones its listener socket. However, the pointer to 'inet_opt' for the new socket has the same value as the original one: as a consequence, on program exit it's possible to observe the following splat: BUG: KASAN: double-free in inet_sock_destruct+0x54f/0x8b0 Free of addr ffff888485950880 by task swapper/25/0 CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Not tainted 6.8.0-rc1+ #609 Hardware name: Supermicro SYS-6027R-72RF/X9DRH-7TF/7F/iTF/iF, BIOS 3.0 07/26/2013 Call Trace: <IRQ> dump_stack_lvl+0x32/0x50 print_report+0xca/0x620 kasan_report_invalid_free+0x64/0x90 __kasan_slab_free+0x1aa/0x1f0 kfree+0xed/0x2e0 inet_sock_destruct+0x54f/0x8b0 __sk_destruct+0x48/0x5b0 rcu_do_batch+0x34e/0xd90 rcu_core+0x559/0xac0 __do_softirq+0x183/0x5a4 irq_exit_rcu+0x12d/0x170 sysvec_apic_timer_interrupt+0x6b/0x80 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x16/0x20 RIP: 0010:cpuidle_enter_state+0x175/0x300 Code: 30 00 0f 84 1f 01 00 00 83 e8 01 83 f8 ff 75 e5 48 83 c4 18 44 89 e8 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc fb 45 85 ed <0f> 89 60 ff ff ff 48 c1 e5 06 48 c7 43 18 00 00 00 00 48 83 44 2b RSP: 0018:ffff888481cf7d90 EFLAGS: 00000202 RAX: 0000000000000000 RBX: ffff88887facddc8 RCX: 0000000000000000 RDX: 1ffff1110ff588b1 RSI: 0000000000000019 RDI: ffff88887fac4588 RBP: 0000000000000004 R08: 0000000000000002 R09: 0000000000043080 R10: 0009b02ea273363f R11: ffff88887fabf42b R12: ffffffff932592e0 R13: 0000000000000004 R14: 0000000000000000 R15: 00000022c880ec80 cpuidle_enter+0x4a/0xa0 do_idle+0x310/0x410 cpu_startup_entry+0x51/0x60 start_secondary+0x211/0x270 secondary_startup_64_no_verify+0x184/0x18b </TASK> Allocated by task 6853: kasan_save_stack+0x1c/0x40 kasan_save_track+0x10/0x30 __kasan_kmalloc+0xa6/0xb0 __kmalloc+0x1eb/0x450 cipso_v4_sock_setattr+0x96/0x360 netlbl_sock_setattr+0x132/0x1f0 selinux_netlbl_socket_post_create+0x6c/0x110 selinux_socket_post_create+0x37b/0x7f0 security_socket_post_create+0x63/0xb0 __sock_create+0x305/0x450 __sys_socket_create.part.23+0xbd/0x130 __sys_socket+0x37/0xb0 __x64_sys_socket+0x6f/0xb0 do_syscall_64+0x83/0x160 entry_SYSCALL_64_after_hwframe+0x6e/0x76 Freed by task 6858: kasan_save_stack+0x1c/0x40 kasan_save_track+0x10/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x12c/0x1f0 kfree+0xed/0x2e0 inet_sock_destruct+0x54f/0x8b0 __sk_destruct+0x48/0x5b0 subflow_ulp_release+0x1f0/0x250 tcp_cleanup_ulp+0x6e/0x110 tcp_v4_destroy_sock+0x5a/0x3a0 inet_csk_destroy_sock+0x135/0x390 tcp_fin+0x416/0x5c0 tcp_data_queue+0x1bc8/0x4310 tcp_rcv_state_process+0x15a3/0x47b0 tcp_v4_do_rcv+0x2c1/0x990 tcp_v4_rcv+0x41fb/0x5ed0 ip_protocol_deliver_rcu+0x6d/0x9f0 ip_local_deliver_finish+0x278/0x360 ip_local_deliver+0x182/0x2c0 ip_rcv+0xb5/0x1c0 __netif_receive_skb_one_core+0x16e/0x1b0 process_backlog+0x1e3/0x650 __napi_poll+0xa6/0x500 net_rx_action+0x740/0xbb0 __do_softirq+0x183/0x5a4 The buggy address belongs to the object at ffff888485950880 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 0 bytes inside of 64-byte region [ffff888485950880, ffff8884859508c0) The buggy address belongs to the physical page: page:0000000056d1e95e refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888485950700 pfn:0x485950 flags: 0x57ffffc0000800(slab|node=1|zone=2|lastcpupid=0x1fffff) page_type: 0xffffffff() raw: 0057ffffc0000800 ffff88810004c640 ffffea00121b8ac0 dead000000000006 raw: ffff888485950700 0000000000200019 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888485950780: fa fb fb ---truncated---

Severity
high
Software
Kernel
Fixed in
6.7.9
Published
2024-04-04

Affected versions

From: 6.7

Until: 6.7.9

Fixed in: 6.7.9

How to fix this CVE

Update your Linux kernel to version 6.7.9 or later to resolve a critical double-free vulnerability in MPTCP socket handling. This issue occurs when an MPTCP server accepts connections and clones listener sockets with shared inet_opt pointers, leading to memory corruption during socket cleanup. Immediate kernel patching is recommended for systems running vulnerable versions 6.7.0 through 6.7.8.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Check current kernel version: uname -r | grep -E '^6\.7\.[0-8]($|-)' && echo 'VULNERABLE' || echo 'Not in vulnerable range'
  2. Verify MPTCP is enabled: cat /boot/config-$(uname -r) | grep CONFIG_MPTCP and confirm it equals 'y' or 'm'
  3. Monitor system logs for double-free crashes: sudo journalctl -xe | grep -i 'double-free\|BUG: KASAN'
  4. After patching, confirm new kernel is running: uname -r and verify version is 6.7.9 or later

FAQ

What is CVE-2024-26782?

CVE-2024-26782 is a double-free memory corruption vulnerability in the Linux kernel's MPTCP implementation where socket cloning during server connection acceptance creates shared inet_opt pointers that are freed twice during socket destruction, causing kernel crashes and potential code execution.

Is CVE-2024-26782 being actively exploited?

No, this vulnerability is not currently listed in the CISA Known Exploited Vulnerabilities catalog and no public exploits are available, though the severity is high (CVSS 7.8) and local privilege escalation is theoretically possible.

What versions of Kernel are affected by CVE-2024-26782?

Kernel versions 6.7.0 through 6.7.8 are affected; version 6.7.9 and later contain the fix.

How do I check if my server is vulnerable to CVE-2024-26782?

Run 'uname -r' and check if the version falls between 6.7.0 and 6.7.8; if yes and MPTCP is enabled (cat /boot/config-$(uname -r) | grep CONFIG_MPTCP), your system is vulnerable.

Does Defensia detect CVE-2024-26782?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2024-26782 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2026-64033CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: RDMA/rtrs: Fix use-after-free in path file creation cleanup In the error path of rtrs_srv_create_path_files(), the sysfs root folders may already have been created and srv_path->kobj may already have been initialized. If a later step fails, the cleanup currently calls kobject_put(&srv_path->kobj) before rtrs_srv_destroy_once_sysfs_root_folders(srv_path). kobject_put() may drop the last reference to srv_path->kobj and invoke the release callback, rtrs_srv_release(), which frees srv_path. The following call to rtrs_srv_destroy_once_sysfs_root_folders(srv_path) then dereferences srv_path internally to access srv_path->srv, resulting in a use-after-free. This failure path is reached before rtrs_srv_create_path_files() returns success, so the successful-path lifetime handling is not involved. Fix this by destroying the sysfs root folders before calling kobject_put(&srv_path->kobj), so srv_path is still valid while the helper accesses it. This issue was found by a static analysis tool I am developing.
CVE-2026-64037CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: wifi: iwlwifi: mld: fix TSO segmentation explosion when AMSDU is disabled When the TLC notification disables AMSDU for a TID, the MLD driver sets max_tid_amsdu_len to the sentinel value 1. The TSO segmentation path in iwl_mld_tx_tso_segment() checks for zero but not for this sentinel, allowing it to reach the num_subframes calculation: num_subframes = (max_tid_amsdu_len + pad) / (subf_len + pad) = (1 + 2) / (1534 + 2) = 0 This zero propagates to iwl_tx_tso_segment() which sets: gso_size = num_subframes * mss = 0 Calling skb_gso_segment() with gso_size=0 creates over 32000 tiny segments from a single GSO skb. This floods the TX ring with ~1024 micro-frames (the rest are purged), creating a massive burst of TX completion events that can lead to memory corruption and a subsequent use-after-free in TCP's retransmit queue (refcount underflow in tcp_shifted_skb, NULL deref in tcp_rack_detect_loss). The MVM driver is immune because it checks mvmsta->amsdu_enabled before reaching the num_subframes calculation. The MLD driver has no equivalent bitmap check and relies solely on max_tid_amsdu_len, which does not catch the sentinel value. Fix this by detecting the sentinel value (max_tid_amsdu_len == 1) at the existing check and falling back to non-AMSDU TSO segmentation. Also add a WARN_ON_ONCE guard after the num_subframes division as defense-in-depth to catch any future code paths that produce zero through a different mechanism.
CVE-2026-100075CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: RDMA/srpt: Fix srpt_alloc_rw_ctxs() unwind counters When srpt_alloc_rw_ctxs() fails partway through a multi-buffer indirect descriptor, the unwind path destroys RDMA contexts but leaves stale n_rw_ctx and n_rdma values (and a dangling rw_ctxs pointer). Later sq_wr_avail accounting in srpt_queue_response() or srpt_write_pending() can then subtract the wrong number of send queue credits. Reset the counters and clear rw_ctxs after freeing the heap allocation before returning an error.
CVE-2026-64035CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: igc: set tx buffer type for SMD frames Sashiko pointed out that igc_fpe_init_smd_frame() initializes igc_tx_buffer fields for an SMD skb, but does not set the buffer type: https://sashiko.dev/#/patchset/20260415025226.114115-1-kohei%40enjuk.jp Since igc_tx_buffer entries are reused, a stale XDP or XSK type can remain and make TX completion use the wrong cleanup path. Set the buffer type to IGC_TX_BUFFER_TYPE_SKB.
CVE-2026-64007CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: netfilter: synproxy: refresh tcphdr after skb_ensure_writable synproxy_tstamp_adjust() rewrites the TCP timestamp option in place and then patches the TCP checksum via inet_proto_csum_replace4() on the caller-supplied tcphdr pointer. Both ipv4_synproxy_hook() and ipv6_synproxy_hook() obtain that pointer with skb_header_pointer() before calling in, so it may either alias skb->head directly or point at the caller's on-stack _tcph buffer. Between obtaining the pointer and using it, the function calls skb_ensure_writable(skb, optend), which on a cloned or non-linear skb invokes pskb_expand_head() and frees the old skb->head. After that point the cached th is stale: caller (ipv[46]_synproxy_hook) th = skb_header_pointer(skb, ..., &_tcph) synproxy_tstamp_adjust(skb, protoff, th, ...) skb_ensure_writable(skb, optend) pskb_expand_head() /* kfree(old skb->head) */ ... inet_proto_csum_replace4(&th->check, ...) /* writes into freed head, or into the caller's stack copy leaving the on-wire checksum stale */ The option bytes are written through skb->data and are fine; only the checksum update goes through th and so lands in the wrong place. The result is either a write into freed slab memory or a packet leaving with a checksum that does not match its payload. Fix by re-deriving th from skb->data + protoff immediately after skb_ensure_writable() succeeds, so the subsequent checksum update targets the linear, writable header.

References

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