CVE-2024-26809

Published Apr 4, 2024

Last updated a year ago

CVSS medium 5.5
Linux Kernel

Overview

AI description

Automated description summarized from trusted sources.

CVE-2024-26809 is a vulnerability in the Linux kernel, specifically within the netfilter subsystem, which is responsible for network packet filtering. The vulnerability occurs in the `nft_set_pipapo` component and arises from releasing elements in a clone operation only from the destroy path. The core issue is that the clone operation already provides a current view of the lookup table. By using this view to destroy the set, it prevents the possibility of destroying elements twice, which could lead to memory corruption or other undefined behavior. The fix for this vulnerability requires specific patches to be applied to the kernel.

Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_set_pipapo: release elements in clone only from destroy path Clone already always provides a current view of the lookup table, use it to destroy the set, otherwise it is possible to destroy elements twice. This fix requires: 212ed75dc5fb ("netfilter: nf_tables: integrate pipapo into commit protocol") which came after: 9827a0e6e23b ("netfilter: nft_set_pipapo: release elements in clone from abort path").
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel, debian_linux

Risk scores

CVSS 3.1

Type
Primary
Base score
5.5
Impact score
3.6
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
NVD-CWE-noinfo

Social media

Hype score
Not currently trending
  1. #Linux #Vulnerability PoC Released: CVE-2024-26809 Exploits nftables Double-Free to Achieve Root Shell https://t.co/S2JYIri86W

    @Komodosec

    6 Jul 2025

    71 Impressions

    0 Retweets

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  2. Linux Kernel hit as PoC exploit for critical nftables flaw CVE-2024-26809 opens door to full root access via double-free attack. #LinuxSecurity #CVE202426809 #KernelExploit https://t.co/qwgN8J0KvR

    @CyberSecTV_eu

    27 May 2025

    75 Impressions

    0 Retweets

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  3. ادمین های سرورهای لینوکسی توجه کنید . به تازگی آسیب پذیری جدیدی با کد شناسایی CVE-2024-26809 و از نوع privilege escalation و RCE برای فایروال nftables در لینوکس منتشر شده است. کر

    @AmirHossein_sec

    18 May 2025

    42 Impressions

    0 Retweets

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  4. Linuxカーネルのnftablesにおける二重解放の脆弱性CVE-2024-26809に対応するPoC(攻撃の概念実証コード)が公表された。nft_pipapo_destroy()の実装における不備。ヒープスプレー及びROPチェーンとの組み合わせでrootへの

    @__kokumoto

    12 May 2025

    2083 Impressions

    6 Retweets

    27 Likes

    4 Bookmarks

    0 Replies

    0 Quotes

  5. CVE-2024-26809: Critical nftables Vulnerability in Linux Kernel Could Lead to Root Access https://t.co/sytmVFZmY6 A critical security flaw has been discovered in the Linux kernel's nftables subsystem, which is responsible for packet filtering in modern Linux distributions. Th

    @f1tym1

    12 May 2025

    22 Impressions

    0 Retweets

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  6. 🔥 PoC Exploit Released for Linux Kernel’s nftables Subsystem Vulnerability | Read more: https://t.co/5ktwmzmkhN A critical Proof-of-Concept (PoC) exploit has been released for a significant vulnerability in the Linux kernel’s nftables subsystem, tracked as CVE-2024-26809.

    @The_Cyber_News

    12 May 2025

    487 Impressions

    1 Retweet

    1 Like

    1 Bookmark

    0 Replies

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  7. 🚨 Double Trouble: How #CVE-2024-26809 Exposes #Linux Systems to Local Privilege Escalation https://t.co/30IexlJTNU

    @UndercodeNews

    12 May 2025

    38 Impressions

    0 Retweets

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  8. 📌 Double-free vulnerability in Linux nftables kernel (CVE-2024-26809) allows attackers to gain root privileges. #CyberSecurity #Linux https://t.co/xmzj5qEQWr https://t.co/lAWd1AuGYQ

    @CyberHub_blog

    12 May 2025

    4 Impressions

    0 Retweets

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  9. PoC Released: CVE-2024-26809 Exploits nftables Double-Free to Achieve Root Shell https://t.co/yd1L3xNBls

    @Dinosn

    12 May 2025

    3261 Impressions

    6 Retweets

    20 Likes

    12 Bookmarks

    0 Replies

    0 Quotes

  10. Linuxカーネルのnftablesサブシステム(net/netfilterモジュール)において、CVE-2024-26809として追跡される深刻な脆弱性が発見された。 これは、nft_pipapo_destroy()関数におけるダブルフリーの不具合で、特定条件下で同

    @yousukezan

    12 May 2025

    1536 Impressions

    0 Retweets

    8 Likes

    4 Bookmarks

    0 Replies

    0 Quotes

  11. 🗣️ PoC Released: CVE-2024-26809 Exploits nftables Double-Free to Achieve Root Shell https://t.co/aQSDECIx09

    @fridaysecurity

    12 May 2025

    31 Impressions

    0 Retweets

    0 Likes

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  12. PoC Released: CVE-2024-26809 Exploits nftables Double-Free to Achieve Root Shell https://t.co/q9upPy6eMe

    @Daily_CyberSec

    12 May 2025

    1428 Impressions

    12 Retweets

    13 Likes

    6 Bookmarks

    0 Replies

    0 Quotes

  13. Top 5 Trending CVEs: 1 - CVE-2025-3776 2 - CVE-2024-26809 3 - CVE-2025-46337 4 - CVE-2025-26529 5 - CVE-2025-32433 #cve #cvetrends #cveshield #cybersecurity https://t.co/4Fua3CAN6W

    @CVEShield

    4 May 2025

    21 Impressions

    0 Retweets

    0 Likes

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    0 Replies

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  14. [1day1line] CVE-2024-26809: Linux Kernel Netfilter Use-After-Free Leading to LPE Vulnerability https://t.co/VRDkQhkeAg This NetFilter LPE vulnerability was submitted to KernelCTF. It's quite a complex vulnerability...

    @hackyboiz

    3 May 2025

    2205 Impressions

    14 Retweets

    61 Likes

    16 Bookmarks

    0 Replies

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Configurations

  1. In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Ensure hugepage is in by slot before checking max mapping level When recovering hugepages in the shadow MMU, verify that the base gfn of the shadow page is actually contained within the target memslot, *before* querying the max mapping level given the shadow page's gfn. Failure to pre-check the validity of the gfn can lead to an out-of-bounds access to the slot's lpage_info (which typically manifests as a host #PF because the lpage_info is vmalloc'd) if the guest creates a hugepage mapping (in its PTEs) that extends "below" the bounds of a memslot. When faulting in memory for a guest, and the size of the guest mapping is greater than KVM's (current) max mapping, then KVM will create a "direct" shadow page (direct in that there are no gPTEs to shadow, and so the target gfn is a direct calculation given the base gfn of the shadow page). The hugepage recovery flow looks for such direct shadow pages, as forcing 4KiB mappings when dirty logging generates the guest > host mapping size case. When the 4KiB restriction is lifted, then KVM can replace the shadow page with a hugepage. But if KVM originally used a smaller mapping than the guest because the range of memory covered by the guest hugepage exceeds the bounds of a memslot, then KVM will link a direct shadow page with a gfn that is outside the bounds of the memslot being used to fault in memory. The rmap entry added for the leaf mapping is correct and within bounds, but the gfn of the leaf SPTE's parent shadow page will be out of bounds. BUG: unable to handle page fault for address: ffffc90000806ffc #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 100000067 P4D 100000067 PUD 1002a7067 PMD 10612f067 PTE 0 Oops: Oops: 0000 [#1] SMP CPU: 13 UID: 1000 PID: 757 Comm: mmu_stress_test Not tainted 7.1.0-rc1-48ce1e26eace-x86_pir_to_irr_comments-vm #341 PREEMPT Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:kvm_mmu_max_mapping_level+0x79/0x2b0 [kvm] Call Trace: <TASK> kvm_mmu_recover_huge_pages+0x21b/0x320 [kvm] kvm_set_memslot+0x1ee/0x590 [kvm] kvm_set_memory_region.part.0+0x3a1/0x4d0 [kvm] kvm_vm_ioctl+0x9bf/0x15d0 [kvm] __x64_sys_ioctl+0x8a/0xd0 do_syscall_64+0xb7/0xbb0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f21c0f1a9bf </TASK> Don't bother pre-checking the bounds of the potential hugepage, i.e. don't check that e.g. sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level + 1) is also within the memslot, as the checks performed by kvm_mmu_max_mapping_level() are a superset of the basic bounds checks. I.e. pre-checking the full range would be a dubious micro-optimization.CVE-2026-63807
  2. In the Linux kernel, the following vulnerability has been resolved: KVM: Replace guest-triggerable BUG_ON() in ioeventfd datamatch with get_unaligned() Drop a BUG_ON() that has been reachable since it was first added, way back in 2009, and instead use get_unaligned() to perform potentially-unaligned accesses. For a given store, KVM x86's emulator tracks the entire value in the destination operand, x86_emulate_ctxt.dst. If the destination is memory, and the target splits multiple pages and/or is emulated MMIO, then KVM handles each fragment independently. E.g. on a page split starting at page offset 0xffc, KVM writes 4 bytes to the first page, then the remaining bytes to the second page, using ctxt->dst as the source for both (with appropriate offsets). If the destination splits a page *and* hits emulated MMIO on the second page, then KVM will complete the write to the first page, then emulate the MMIO access to the second page. If there is a datamatch-enabled ioeventfd at offset 0 of the second page, then KVM will process the remainder of the store as a potential ioeventfd signal. Putting it all together, if the guest emits a store that splits a page starting at page offset N, and the second page has a datamatch-enabled ioeventfd at offset 0, then KVM will check for datamatch using &dst.valptr[N] as the source. Due to dst (and thus dst.valptr) being 32-byte aligned, if N is not aligned to @len, the BUG_ON() fires. E.g. with a 16-byte store at page offset 0xffc, to an ioeventfd of len 8, all initial checks in ioeventfd_in_range() will succeed, and the BUG_ON() fires due to @val being 4-byte aligned, but not 8-byte aligned. ------------[ cut here ]------------ kernel BUG at arch/x86/kvm/../../../virt/kvm/eventfd.c:783! Oops: invalid opcode: 0000 [#1] SMP CPU: 0 UID: 1000 PID: 615 Comm: repro Not tainted 7.1.0-rc2-ff238429d1ea #365 PREEMPT Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:ioeventfd_write+0x6c/0x70 [kvm] Call Trace: <TASK> __kvm_io_bus_write+0x85/0xb0 [kvm] kvm_io_bus_write+0x53/0x80 [kvm] vcpu_mmio_write+0x66/0xf0 [kvm] emulator_read_write_onepage+0x12a/0x540 [kvm] emulator_read_write+0x109/0x2b0 [kvm] x86_emulate_insn+0x4f8/0xfb0 [kvm] x86_emulate_instruction+0x181/0x790 [kvm] kvm_mmu_page_fault+0x313/0x630 [kvm] vmx_handle_exit+0x18a/0x590 [kvm_intel] kvm_arch_vcpu_ioctl_run+0xc81/0x1c90 [kvm] kvm_vcpu_ioctl+0x2d5/0x970 [kvm] __x64_sys_ioctl+0x8a/0xd0 do_syscall_64+0xb7/0x890 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f19c931a9bf </TASK> Modules linked in: kvm_intel kvm irqbypass ---[ end trace 0000000000000000 ]--- In a perfect world, the fix would be to simply delete the BUG_ON(), as KVM x86 doesn't perform alignment checks on "normal" memory accesses at CPL0. Sadly, C99 ruins all the fun; while the x86 architecture plays nice, dereferencing an unaligned pointer directly is undefined behavior in C, e.g. triggers splats when running with CONFIG_UBSAN_ALIGNMENT=y.CVE-2026-63806
  3. In the Linux kernel, the following vulnerability has been resolved: hdlc_ppp: sync per-proto timers before freeing hdlc state Each PPP control protocol (LCP/IPCP/IPV6CP) embedded in struct ppp registers a timer via timer_setup(). That struct ppp is the hdlc->state allocation, which detach_hdlc_protocol() frees with kfree() in both teardown paths: unregister_hdlc_device() and the re-attach inside attach_hdlc_protocol(). The ppp proto never registered a .detach callback, so detach_hdlc_protocol() performs no timer synchronization before the kfree(). The only cancel, timer_delete(&proto->timer) in ppp_cp_event(), is partial (it does not wait for a running callback) and only runs on the ->CLOSED transition; ppp_stop()/ppp_close() do not sync either. A ppp_timer callback already executing (blocked on ppp->lock) survives the kfree and then dereferences proto->state / ppp->lock in freed memory, leading to a use-after-free. Fix this by adding a .detach helper that calls timer_shutdown_sync() on every per-proto timer. detach_hdlc_protocol() invokes proto->detach(dev) before kfree(hdlc->state), so timer_shutdown_sync() now runs on both free paths. timer_shutdown_sync() is used instead of timer_delete_sync() because the keepalive path re-arms the timer through add_timer()/mod_timer() and shutdown blocks any re-activation during teardown. Initialize the per-protocol timers in ppp_ioctl() when the protocol is attached, and remove the now-redundant timer_setup() from ppp_start(), so that the timers are initialized exactly once at attach time and ppp_timer_release() never operates on uninitialized timer_list structures. attach_hdlc_protocol() uses kmalloc() (not kzalloc), so struct ppp's protos[i].timer is uninitialized garbage until the first timer_setup(); without this init-at-attach, attaching the PPP protocol without ever bringing the device up would leave timer_shutdown_sync() operating on uninitialized memory in .detach. Moving the init out of ppp_start() (which only runs on NETDEV_UP) into the attach path makes the initialization unconditional and avoids initializing the same timer_list twice. This bug was found by static analysis.CVE-2026-63803