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CVE-2026-72297
net: atm: reject out-of-range traffic classes in QoS validation
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem net/atm. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-72297 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixed | 6.1.180-1 | Update the kernel and reboot. Fixed in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.100-1 | Update the kernel and reboot. Fixed in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Reject ATM traffic classes above ATM_ANYCLASS in check_tp(). SO_ATMQOS stores the supplied QoS after check_qos() succeeds, so accepting larger values leaves invalid traffic_class values in vcc->qos. That bad state later reaches pvc_info(), which indexes class_name[] with vcc->qos.{rx,tp}.traffic_class. Values above ATM_ANYCLASS cause an out-of-bounds read when /proc/net/atm/pvc is read. Tighten the existing QoS validation so invalid traffic_class values are rejected at the point where user supplied QoS is accepted.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
net/atm/common.c
- What this is
- ATMMAINTAINERS section matched on net/atm/ · linux-atm-general@lists.sourceforge.net · Maintained
- Kernel module
- atm
Check it on the machine
grep -w CONFIG_ATM /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w atmPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- M
- a module where it is built at all; some flavours do not build it
- Build switch
- CONFIG_ATM
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-15 (2 months ago)source
- CVSS
- 7.1 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.16%, higher than 5.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/atm
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.12 | 5.10.261 | 1a6dda72455b |
| 2.6.12 | 5.15.212 | 2b3e241729e8 |
| 2.6.12 | 6.1.178 | 367acd288bc6 |
| 2.6.12 | 6.6.145 | 513f820b3f0c |
| 2.6.12 | 6.12.97 | 15444b57fdc6 |
| 2.6.12 | 6.18.40 | e62adb157c2e |
| 2.6.12 | 7.1.5 | 806b7b6edc84 |
| 2.6.12 | 7.2 | cdf19f380e46 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- Exploitation requires local setsockopt(SO_ATMQOS) on an AF_ATMPVC socket and reading /proc/net/atm/pvc; no remote network packet or protocol handler reaches check_tp() or pvc_info().
- AC:LAttack complexity, low
- On systems with an existing ATM PVC device, an attacker deterministically sets an out-of-range traffic_class via SO_ATMQOS before connect and triggers the OOB read by reading /proc/net/atm/pvc with no race or special memory layout needed.
- PR:LPrivileges required, low
- No capability check guards SO_ATMQOS on unconnected sockets; any unprivileged local user in init_net can create AF_ATMPVC sockets (module autoloadable) and read world-readable /proc/net/atm/pvc without CAP_NET_ADMIN.
- UI:NUser interaction, none
- The attacker controls both poisoning vcc->qos via setsockopt and triggering pvc_info() by reading procfs; no victim action or cooperation is required.
- S:UScope, unchanged
- Impact is kernel memory disclosure within the host kernel security boundary; no VM escape, IOMMU bypass, or sandbox boundary crossing occurs.
- C:HConfidentiality impact, high
- Out-of-bounds indexing of class_name[] loads adjacent kernel pointers that seq_printf() dereferences with %s, disclosing kernel memory contents into the procfs read buffer visible to the attacker.
- I:NIntegrity impact, none
- The flaw is an out-of-bounds read of static pointer tables with no memory corruption, arbitrary write, or control-flow hijack primitive; kernel or user data integrity is not modified.
- A:HAvailability impact, high
- Dereferencing attacker-influenced out-of-bounds pointers via %s can fault on unmappable addresses and oops the kernel; even without reliable crash, OOB kernel reads carry high availability risk per conservative scoring.