CVE-2025-38185
NoneCVSS
—
EPSS
0.2%
Published
Jul 4, 2025
CISA due date
—
Cloudanix analysis
A bug in how the Linux kernel handles certain network messages can let attackers on the same machine cause crashes or waste memory resources.
- Exploitation
- Local Privilege
- Attacker needs
- Local User
- Complexity
- Low
- Impact
- Denial Of Service
- Component
- OS kernel
- Class
- Improper Input Validation
- Remediation
- Upgrade
- Effort
- Medium
- Patch risk
- Low
What it actually does
Use of uninitialized value in atmtcp_c_send when skb length is zero after vcc_sendmsg copies userspace data, combined with failure to call dev_kfree_skb and adjust sk_wmem_alloc leading to skb and socket leaks.
Why it matters to the business
Systems using ATM networking in the Linux kernel, including certain container-optimized and agent deployments, face risk of kernel instability or resource exhaustion; widespread kernel exposure increases operational urgency despite low exploitation probability.
How an attack unfolds
An attacker with local access crafts a zero-length sendmsg on an ATM VCC socket, triggering atmtcp_c_send to access uninitialized skb data and leak memory without proper cleanup; similar Linux kernel sendmsg flaws have been chained by advanced campaigns for privilege escalation in container environments.
How to fix it
Upgrade Linux kernel to commit c19c0943424b412a84fdf178e6c71fe5480e4f0f or later; update affected Chainguard packages to versions 7.66.1-r2 or newer for datadog-agent-fips, datadog-cluster-agent-fips and related images.
How to confirm the fix worked
Verify kernel source contains the atmtcp_c_send length check and dev_kfree_skb call before atm_pop_raw; confirm package versions match fixed releases and test sendmsg with zero-length ATM payloads under KMSAN or similar sanitizers.
Typical attack path
- Obtain local code execution or user access on target host
- Create an ATM VCC socket and invoke sendmsg with zero-length payload
- Trigger vcc_sendmsg path that calls atmtcp_c_send without length validation
- Cause uninitialized value access and prevent skb release plus accounting revert
- Escalate via kernel panic, information leak, or follow-on memory corruption
How to detect it
Review kernel logs for KMSAN uninit-value reports in atmtcp_c_send or vcc_sendmsg; search audit and syscall logs for unusual ATM socket creation followed by zero-length sendmsg attempts from untrusted processes.
What your security team should do
- Prioritize kernel and datadog agent updates on all systems exposing ATM networking or running container workloads
- Monitor EPSS trend and threat actor activity around Linux kernel sendmsg paths for rapid reassessment
- Restrict unprivileged local socket creation where ATM protocols are unnecessary
- Apply compensating controls such as seccomp filters blocking relevant syscalls until patches are deployed
The record
In the Linux kernel, the following vulnerability has been resolved: atm: atmtcp: Free invalid length skb in atmtcp_c_send(). syzbot reported the splat below. [0] vcc_sendmsg() copies data passed from userspace to skb and passes it to vcc->dev->ops->send(). atmtcp_c_send() accesses skb->data as struct atmtcp_hdr after checking if skb->len is 0, but it's not enough. Also, when skb->len == 0, skb and sk (vcc) were leaked because dev_kfree_skb() is not called and sk_wmem_alloc adjustment is missing to revert atm_account_tx() in vcc_sendmsg(), which is expected to be done in atm_pop_raw(). Let's properly free skb with an invalid length in atmtcp_c_send(). [0]: BUG: KMSAN: uninit-value in atmtcp_c_send+0x255/0xed0 drivers/atm/atmtcp.c:294 atmtcp_c_send+0x255/0xed0 drivers/atm/atmtcp.c:294 vcc_sendmsg+0xd7c/0xff0 net/atm/common.c:644 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x330/0x3d0 net/socket.c:727 ____sys_sendmsg+0x7e0/0xd80 net/socket.c:2566 ___sys_sendmsg+0x271/0x3b0 net/socket.c:2620 __sys_sendmsg net/socket.c:2652 [inline] __do_sys_sendmsg net/socket.c:2657 [inline] __se_sys_sendmsg net/socket.c:2655 [inline] __x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2655 x64_sys_call+0x32fb/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Uninit was created at: slab_post_alloc_hook mm/slub.c:4154 [inline] slab_alloc_node mm/slub.c:4197 [inline] kmem_cache_alloc_node_noprof+0x818/0xf00 mm/slub.c:4249 kmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:579 __alloc_skb+0x347/0x7d0 net/core/skbuff.c:670 alloc_skb include/linux/skbuff.h:1336 [inline] vcc_sendmsg+0xb40/0xff0 net/atm/common.c:628 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x330/0x3d0 net/socket.c:727 ____sys_sendmsg+0x7e0/0xd80 net/socket.c:2566 ___sys_sendmsg+0x271/0x3b0 net/socket.c:2620 __sys_sendmsg net/socket.c:2652 [inline] __do_sys_sendmsg net/socket.c:2657 [inline] __se_sys_sendmsg net/socket.c:2655 [inline] __x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2655 x64_sys_call+0x32fb/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f CPU: 1 UID: 0 PID: 5798 Comm: syz-executor192 Not tainted 6.16.0-rc1-syzkaller-00010-g2c4a1f3fe03e #0 PREEMPT(undef) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Debian:11 | linux | 0 | No fix |
| Debian:12 | linux | 0 | No fix |
| Debian:13 | linux | 0 | No fix |
| Debian:14 | linux | 0 | 6.12.35-1 |
| Linux | Kernel | 2.6.12 | 5.4.295 |
| Mageia:9 | kernel | 0 | 6.6.101-1.mga9 |
| Mageia:9 | kernel-linus | 0 | 6.6.101-1.mga9 |
| Mageia:9 | kmod-virtualbox | 0 | 7.1.10-7.mga9 |
| Mageia:9 | kmod-xtables-addons | 0 | 3.24-83.mga9 |
| Mageia:9 | wireless-regdb | 0 | 20250710-1.mga9 |
| SUSE:Linux Enterprise High Availability Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.70.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.70.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6-RT_Update_15 | 0 | 1-150600.1.3.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6_Update_15 | 0 | 1-150600.13.3.2 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-64kb | 0 | 6.4.0-150600.23.70.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.70.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-default-base | 0 | 6.4.0-150600.23.70.1.150600.12.30.2 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-source | 0 | 6.4.0-150600.23.70.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-zfcpdump | 0 | 6.4.0-150600.23.70.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-docs | 0 | 6.4.0-150600.23.70.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-obs-build | 0 | 6.4.0-150600.23.70.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-source | 0 | 6.4.0-150600.23.70.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-syms | 0 | 6.4.0-150600.23.70.1 |
| SUSE:Linux Enterprise Module for Legacy 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.70.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP6 | kernel-azure | 0 | 6.4.0-150600.8.52.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP6 | kernel-source-azure | 0 | 6.4.0-150600.8.52.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP6 | kernel-syms-azure | 0 | 6.4.0-150600.8.52.1 |
| SUSE:Linux Enterprise Workstation Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.70.1 |
| SUSE:Real Time Module 15 SP6 | kernel-rt | 0 | 6.4.0-150600.10.52.1 |
| SUSE:Real Time Module 15 SP6 | kernel-rt_debug | 0 | 6.4.0-150600.10.52.1 |
| SUSE:Real Time Module 15 SP6 | kernel-source-rt | 0 | 6.4.0-150600.10.52.1 |
| SUSE:Real Time Module 15 SP6 | kernel-syms-rt | 0 | 6.4.0-150600.10.52.1 |
| openSUSE:Leap 15.6 | dtb-aarch64 | 0 | 6.4.0-150600.23.70.1 |
| openSUSE:Leap 15.6 | kernel-64kb | 0 | 6.4.0-150600.23.70.1 |
| openSUSE:Leap 15.6 | kernel-azure | 0 | 6.4.0-150600.8.52.1 |
| openSUSE:Leap 15.6 | kernel-debug | 0 | 6.4.0-150600.23.70.1 |
| openSUSE:Leap 15.6 | kernel-default | 0 | 6.4.0-150600.23.70.1 |
| openSUSE:Leap 15.6 | kernel-default-base | 0 | 6.4.0-150600.23.70.1.150600.12.30.2 |
| openSUSE:Leap 15.6 | kernel-docs | 0 | 6.4.0-150600.23.70.1 |
| openSUSE:Leap 15.6 | kernel-kvmsmall | 0 | 6.4.0-150600.23.70.1 |
| openSUSE:Leap 15.6 | kernel-obs-build | 0 | 6.4.0-150600.23.70.1 |
| openSUSE:Leap 15.6 | kernel-obs-qa | 0 | 6.4.0-150600.23.70.1 |
| openSUSE:Leap 15.6 | kernel-rt | 0 | 6.4.0-150600.10.52.1 |
| openSUSE:Leap 15.6 | kernel-rt_debug | 0 | 6.4.0-150600.10.52.1 |
| openSUSE:Leap 15.6 | kernel-source | 0 | 6.4.0-150600.23.70.1 |
| openSUSE:Leap 15.6 | kernel-source-azure | 0 | 6.4.0-150600.8.52.1 |
| openSUSE:Leap 15.6 | kernel-source-rt | 0 | 6.4.0-150600.10.52.1 |
| openSUSE:Leap 15.6 | kernel-syms | 0 | 6.4.0-150600.23.70.1 |
| openSUSE:Leap 15.6 | kernel-syms-azure | 0 | 6.4.0-150600.8.52.1 |
| openSUSE:Leap 15.6 | kernel-syms-rt | 0 | 6.4.0-150600.10.52.1 |
| openSUSE:Leap 15.6 | kernel-zfcpdump | 0 | 6.4.0-150600.23.70.1 |
| openSUSE:Leap 16.0 | dtb-aarch64 | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-64kb | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-default | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-default-base | 0 | 6.12.0-160000.6.1.160000.2.4 |
| openSUSE:Leap 16.0 | kernel-docs | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-kvmsmall | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-obs-build | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-obs-qa | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-rt | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-source | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-syms | 0 | 6.12.0-160000.6.1 |
| openSUSE:Leap 16.0 | kernel-zfcpdump | 0 | 6.12.0-160000.6.1 |
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