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CVE-2026-53270
ipvs: clear the svc scheduler ptr early on edit
Published 2026-06-25 (4 months ago) by the Linux kernel CNA. Subsystem include/net. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-53270 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 | fixedDLA-4665-1 · 2026-07-03 · text | 6.1.176-1 | Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
ip_vs_edit_service() while unbinding the old scheduler clears the svc->scheduler ptr after the scheduler module initiates RCU callbacks. This can cause packets to use the old scheduler at the time when svc->sched_data is already freed after RCU grace period. Fix it by clearing the ptr early in ip_vs_unbind_scheduler(), before the done_service method schedules any RCU callbacks. Also, if the new scheduler fails to initialize when replacing the old scheduler, try to restore the old scheduler while still returning the error code.
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.
include/net/ip_vs.h
net/netfilter/ipvs/ip_vs_ctl.c
net/netfilter/ipvs/ip_vs_sched.c
- What this is
- IPVSMAINTAINERS section matched on include/net/ip_vs.h · netdev@vger.kernel.org · Maintained
- Kernel module
- ip_vs
Check it on the machine
grep -wE 'CONFIG_IP_VS|CONFIG_NETFILTER' /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 ip_vsPrints 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 as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sidm
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switches
- CONFIG_IP_VS, CONFIG_NETFILTER
- Reads as
- all on means the file is compiled; any one off means it is not.
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
- 2026-06-25 (4 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.12%, higher than 1.7% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- include/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.2 | 5.10.259 | d10730a1f2ca |
| 4.2 | 5.15.210 | e4feec317403 |
| 4.2 | 6.1.176 | 7d4f50045117 |
| 4.2 | 6.6.143 | c6376b9b1b4d |
| 4.2 | 6.12.94 | 14e4689c113b |
| 4.2 | 6.18.36 | 25918720ba97 |
| 4.2 | 7.0.13 | 19a9493faa4b |
| 4.2 | 7.1 | 193989cc6d80 |
| 3.18.23 | 0 | 0 |
| 4.1.11 | 0 | 0 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4671-1 | 2026-07-05 | bullseye 6.1.176-1~deb11u1 | tracker |
| DLA-4665-1 | 2026-07-03 | bookworm 6.1.176-1 | tracker |
| DLA-4664-1 | 2026-07-03 | bullseye 5.10.259-1 | tracker |
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
- The vulnerable transition is reached through local IPVS service-edit control paths such as `setsockopt(IP_VS_SO_SET_EDIT)` or IPVS generic netlink; packets exercise the stale scheduler afterward, but the attacker must initiate the local service edit.
- AC:LAttack complexity, low
- The attacker can control both sides of the condition by changing the scheduler and generating new TCP/UDP/SCTP traffic to the service, so this is not dependent on an uncontrollable race.
- PR:LPrivileges required, low
- The legacy setsockopt path checks `CAP_NET_ADMIN` in the socket network namespace, which is reachable by an unprivileged local user via user and network namespaces in plausible deployments.
- UI:NUser interaction, none
- No victim interaction is needed once the attacker has local access and namespace privileges; the attacker can create/edit the IPVS service and send triggering traffic.
- S:UScope, unchanged
- The impact is kernel memory corruption within the same host security authority, not a VM, IOMMU, or separate security-scope escape.
- C:HConfidentiality impact, high
- This is an RCU use-after-free of scheduler-private `svc->sched_data`, and freed scheduler state can be reused and dereferenced by packet scheduling, making high confidentiality impact defensible.
- I:HIntegrity impact, high
- Several affected schedulers write through the stale `sched_data` pointer, so the UAF can plausibly become arbitrary kernel memory corruption or control-flow compromise.
- A:HAvailability impact, high
- At minimum the stale scheduler pointer can dereference freed scheduler state during packet processing and crash or panic the kernel.