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Fencer Vulns
high 7.8

CVE-2025-21858 json

geneve: Fix use-after-free in geneve_find_dev().

published 2025-03-12 19 mo ago modified 2026-10-15 25 d ago also EUVD-2025-6291

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 16%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

geneve: Fix use-after-free in geneve_find_dev().

syzkaller reported a use-after-free in geneve_find_dev() [0] without repro.

geneve_configure() links struct geneve_dev.next to net_generic(net, geneve_net_id)->geneve_list.

The net here could differ from dev_net(dev) if IFLA_NET_NS_PID, IFLA_NET_NS_FD, or IFLA_TARGET_NETNSID is set.

When dev_net(dev) is dismantled, geneve_exit_batch_rtnl() finally calls unregister_netdevice_queue() for each dev in the netns, and later the dev is freed.

However, its geneve_dev.next is still linked to the backend UDP socket netns.

Then, use-after-free will occur when another geneve dev is created in the netns.

Let's call geneve_dellink() instead in geneve_destroy_tunnels().

[0]: BUG: KASAN: slab-use-after-free in geneve_find_dev drivers/net/geneve.c:1295 [inline] BUG: KASAN: slab-use-after-free in geneve_configure+0x234/0x858 drivers/net/geneve.c:1343 Read of size 2 at addr ffff000054d6ee24 by task syz.1.4029/13441

CPU: 1 UID: 0 PID: 13441 Comm: syz.1.4029 Not tainted 6.13.0-g0ad9617c78ac #24 dc35ca22c79fb82e8e7bc5c9c9adafea898b1e3d Hardware name: linux,dummy-virt (DT) Call trace: show_stack+0x38/0x50 arch/arm64/kernel/stacktrace.c:466 (C) __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xbc/0x108 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x16c/0x6f0 mm/kasan/report.c:489 kasan_report+0xc0/0x120 mm/kasan/report.c:602 __asan_report_load2_noabort+0x20/0x30 mm/kasan/report_generic.c:379 geneve_find_dev drivers/net/geneve.c:1295 [inline] geneve_configure+0x234/0x858 drivers/net/geneve.c:1343 geneve_newlink+0xb8/0x128 drivers/net/geneve.c:1634 rtnl_newlink_create+0x23c/0x868 net/core/rtnetlink.c:3795 __rtnl_newlink net/core/rtnetlink.c:3906 [inline] rtnl_newlink+0x1054/0x1630 net/core/rtnetlink.c:4021 rtnetlink_rcv_msg+0x61c/0x918 net/core/rtnetlink.c:6911 netlink_rcv_skb+0x1dc/0x398 net/netlink/af_netlink.c:2543 rtnetlink_rcv+0x34/0x50 net/core/rtnetlink.c:6938 netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline] netlink_unicast+0x618/0x838 net/netlink/af_netlink.c:1348 netlink_sendmsg+0x5fc/0x8b0 net/netlink/af_netlink.c:1892 sock_sendmsg_nosec net/socket.c:713 [inline] __sock_sendmsg net/socket.c:728 [inline] ____sys_sendmsg+0x410/0x6f8 net/socket.c:2568 ___sys_sendmsg+0x178/0x1d8 net/socket.c:2622 __sys_sendmsg net/socket.c:2654 [inline] __do_sys_sendmsg net/socket.c:2659 [inline] __se_sys_sendmsg net/socket.c:2657 [inline] __arm64_sys_sendmsg+0x12c/0x1c8 net/socket.c:2657 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x90/0x278 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x13c/0x250 arch/arm64/kernel/syscall.c:132 do_el0_svc+0x54/0x70 arch/arm64/kernel/syscall.c:151 el0_svc+0x4c/0xa8 arch/arm64/kernel/entry-common.c:744 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:762 el0t_64_sync+0x198/0x1a0 arch/arm64/kernel/entry.S:600

Allocated by task 13247: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x30/0x68 mm/kasan/common.c:68 kasan_save_alloc_info+0x44/0x58 mm/kasan/generic.c:568 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0x84/0xa0 mm/kasan/common.c:394 kasan_kmalloc include/linux/kasan.h:260 [inline] __do_kmalloc_node mm/slub.c:4298 [inline] __kmalloc_node_noprof+0x2a0/0x560 mm/slub.c:4304 __kvmalloc_node_noprof+0x9c/0x230 mm/util.c:645 alloc_netdev_mqs+0xb8/0x11a0 net/core/dev.c:11470 rtnl_create_link+0x2b8/0xb50 net/core/rtnetlink.c:3604 rtnl_newlink_create+0x19c/0x868 net/core/rtnetlink.c:3780 __rtnl_newlink net/core/rtnetlink.c:3906 [inline] rtnl_newlink+0x1054/0x1630 net/core/rtnetlink.c:4021 rtnetlink_rcv_msg+0x61c/0x918 net/core/rtnetlink.c:6911 netlink_rcv_skb+0x1dc/0x398 net/netlink/af_netlink.c:2543 rtnetlink_rcv+0x34/0x50 net/core/rtnetlink.c:6938 netlink_unicast_kernel net/netlink/af_n ---truncated---

Patch / fix

  • Linux Linux 5.4.291, 5.10.235, 5.15.179, 6.1.130, 6.6.80, 6.12.17, 6.13.5, 6.14
  • linux Debian 12 6.1.133-1
  • linux Debian 14, Debian 13 6.12.17-1

debian advisories DEBIAN-CVE-2025-21858

  • linux Ubuntu 20.04 LTS 5.4.0-216.236
  • linux Ubuntu 22.04 LTS 5.15.0-140.150
  • linux Ubuntu 24.04 LTS 6.8.0-78.78
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1146.156
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1084.91
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1035.37
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1149.158
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1083.92

ubuntu advisories UBUNTU-CVE-2025-21858

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 8 4.18.0-553.132.1.el8_10
  • perf RHEL 8 4.18.0-553.132.1.el8_10
  • bpftool RHEL 8 4.18.0-553.132.1.el8_10
  • kernel-core RHEL 8 4.18.0-553.132.1.el8_10
  • kernel-tools RHEL 8 4.18.0-553.132.1.el8_10
  • python3-perf RHEL 8 4.18.0-553.132.1.el8_10
  • kernel-modules RHEL 8 4.18.0-553.132.1.el8_10
  • kernel-zfcpdump RHEL 8 4.18.0-553.132.1.el8_10

red hat advisories RHSA-2026:26570RHSA-2026:26563RHSA-2026:26535RHSA-2026:25121RHSA-2026:25120

  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
  • kernel-syms-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
  • kernel-source-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.20.3.1
  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.3.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.3.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.3.1
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.3.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.3.1

suse advisories SUSE-SU-2025:01967-1SUSE-SU-2025:01951-1SUSE-SU-2025:01919-1SUSE-SU-2025:20192-1SUSE-SU-2025:20270-1SUSE-SU-2025:20190-1

  • kernel-rt AlmaLinux 8 4.18.0-553.132.1.rt7.473.el8_10
  • kernel-rt-core AlmaLinux 8 4.18.0-553.132.1.rt7.473.el8_10
  • kernel-rt-modules AlmaLinux 8 4.18.0-553.132.1.rt7.473.el8_10
  • kernel-rt-debug-core AlmaLinux 8 4.18.0-553.132.1.rt7.473.el8_10
  • kernel-rt-debug-modules AlmaLinux 8 4.18.0-553.132.1.rt7.473.el8_10
  • kernel-rt-modules-extra AlmaLinux 8 4.18.0-553.132.1.rt7.473.el8_10
  • kernel-rt-debug-modules-extra AlmaLinux 8 4.18.0-553.132.1.rt7.473.el8_10
  • kernel AlmaLinux 8 4.18.0-553.132.1.el8_10

almalinux advisories ALSA-2026:25120ALSA-2026:25121

  • kernel Rocky Linux 8 4.18.0-553.132.1.el8_10.cloud.0.1
  • kernel-rt Rocky Linux 8 4.18.0-553.132.1.rt7.473.el8_10
  • kernel Rocky Linux 8 4.18.0-553.132.1.el8_10

rocky linux advisories RXSA-2026:25121RLSA-2026:25120RLSA-2026:25121

  • kernel Azure Linux 3.0 6.6.82.1-1
  • kernel CBL-Mariner 2.0 5.15.179.1-1

azure linux advisories AZL-58515AZL-58584

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-21858 updated cvss 7.3

kernel: geneve: Fix use-after-free in geneve_find_dev().

  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +82 more
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix available
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.132.1.el8_10, kernel 4.18.0-553.132.1.el8_10, bpftool 4.18.0-553.132.1.el8_10, kernel-core 4.18.0-553.132.1.el8_10, kernel-tools 4.18.0-553.132.1.el8_10, python3-perf 4.18.0-553.132.1.el8_10, +15 more
    fixed: vendor fix RHSA-2026:25121
  • Red Hat Enterprise Linux BaseOS AUS (v.8.4) perf 4.18.0-305.194.1.el8_4, kernel 4.18.0-305.194.1.el8_4, bpftool 4.18.0-305.194.1.el8_4, kernel-core 4.18.0-305.194.1.el8_4, kernel-tools 4.18.0-305.194.1.el8_4, python3-perf 4.18.0-305.194.1.el8_4, +8 more
    fixed: vendor fix RHSA-2026:26535
  • Red Hat Enterprise Linux BaseOS AUS (v.8.6) perf 4.18.0-372.196.1.el8_6, kernel 4.18.0-372.196.1.el8_6, bpftool 4.18.0-372.196.1.el8_6, kernel-core 4.18.0-372.196.1.el8_6, kernel-tools 4.18.0-372.196.1.el8_6, python3-perf 4.18.0-372.196.1.el8_6, +8 more
    fixed: vendor fix RHSA-2026:26570
  • Red Hat Enterprise Linux BaseOS E4S (v.8.8) perf 4.18.0-477.147.1.el8_8, kernel 4.18.0-477.147.1.el8_8, bpftool 4.18.0-477.147.1.el8_8, kernel-core 4.18.0-477.147.1.el8_8, kernel-tools 4.18.0-477.147.1.el8_8, python3-perf 4.18.0-477.147.1.el8_8, +9 more
    fixed: vendor fix RHSA-2026:26563
  • Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4) perf 4.18.0-305.194.1.el8_4, kernel 4.18.0-305.194.1.el8_4, bpftool 4.18.0-305.194.1.el8_4, kernel-core 4.18.0-305.194.1.el8_4, kernel-tools 4.18.0-305.194.1.el8_4, python3-perf 4.18.0-305.194.1.el8_4, +8 more
    fixed: vendor fix RHSA-2026:26535
  • Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.6) perf 4.18.0-372.196.1.el8_6, kernel 4.18.0-372.196.1.el8_6, bpftool 4.18.0-372.196.1.el8_6, kernel-core 4.18.0-372.196.1.el8_6, kernel-tools 4.18.0-372.196.1.el8_6, python3-perf 4.18.0-372.196.1.el8_6, +8 more
    fixed: vendor fix RHSA-2026:26570
show 4 more
  • Red Hat Enterprise Linux BaseOS TUS (v.8.8) perf 4.18.0-477.147.1.el8_8, kernel 4.18.0-477.147.1.el8_8, bpftool 4.18.0-477.147.1.el8_8, kernel-core 4.18.0-477.147.1.el8_8, kernel-tools 4.18.0-477.147.1.el8_8, python3-perf 4.18.0-477.147.1.el8_8, +8 more
    fixed: vendor fix RHSA-2026:26563
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.132.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.132.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.132.1.el8_10
    fixed: vendor fix RHSA-2026:25121
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.132.1.rt7.473.el8_10, kernel-rt-kvm 4.18.0-553.132.1.rt7.473.el8_10, kernel-rt-core 4.18.0-553.132.1.rt7.473.el8_10, kernel-rt-modules 4.18.0-553.132.1.rt7.473.el8_10, kernel-rt-debug-kvm 4.18.0-553.132.1.rt7.473.el8_10, kernel-rt-debug-core 4.18.0-553.132.1.rt7.473.el8_10, +4 more Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.132.1.rt7.473.el8_10, kernel-rt-core 4.18.0-553.132.1.rt7.473.el8_10, kernel-rt-modules 4.18.0-553.132.1.rt7.473.el8_10, kernel-rt-debug-core 4.18.0-553.132.1.rt7.473.el8_10, kernel-rt-debug-modules 4.18.0-553.132.1.rt7.473.el8_10, kernel-rt-modules-extra 4.18.0-553.132.1.rt7.473.el8_10, +2 more
    fixed: vendor fix RHSA-2026:25120
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-26-295-16 updated cvss 7.8

Siemens SIMATIC S7-1500 TM MFP

  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
    affected: mitigation, no fix available

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

cisa ICSA-24-102-01 updated cvss 7.8

Siemens SIMATIC S7-1500 TM MFP

  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
    affected: mitigation, no fix available

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
19 mo ago

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CISA ADP 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux
  • Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.