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CVE-2026-74305
bpf: Tighten cgroup storage cookie checks for prog arrays
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem kernel/bpf. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-74305 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
The fix in commit abad3d0bad72 ("bpf: Fix oob access in cgroup local storage") is still incomplete. The prog-array compatibility check treats a program with no cgroup storage as compatible with any stored storage cookie. This allows a storage-less program to bridge a tail call chain between an entry program and a storage-using callee even though cgroup local storage at runtime still follows the caller's context, that is, A -> B(no storage) -> C(storage) path. Requiring exact cookie equality would break the legitimate case of a storage-less leaf program being tail called from a storage-using one. Instead, only accept a zero storage cookie if the program cannot perform tail calls itself. This keeps A -> B(no storage) working while rejecting the A -> B(no storage) -> C(storage) bridge.
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.
kernel/bpf/core.c
- What this is
- BPF [CORE]MAINTAINERS section matched on kernel/bpf/core.c · bpf@vger.kernel.org · Maintained
Check it on the machine
grep -w CONFIG_BPF /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.
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sidy
- y
- built into the kernel image on every flavour - only a patch removes it
- Build switch
- CONFIG_BPF
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
- 7.8 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
- 0.18%, higher than 6.6% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- kernel/bpf
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.15.192 | 5.15.212 | 87177497cca9 |
| 6.1.151 | 6.1.178 | 1c762d286984 |
| 6.6.105 | 6.6.145 | eb73056ce2a6 |
| 6.12.46 | 6.12.97 | 9ca06849c423 |
| 6.17 | 6.18.40 | 46fbafe3d2d5 |
| 6.17 | 7.1.5 | cb22dc79528e |
| 6.17 | 7.2 | 10627ddc0167 |
| 6.16.1 | 0 | 0 |
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 bpf() syscalls to load cgroup BPF programs/maps, populate a prog array, attach or test-run them; per kernel guidance BPF/cgroup hooks are Local even when later triggered by sockets or packets.
- AC:LAttack complexity, low
- The attacker fully controls crafting programs A/B/C, prog-array insertion order, and triggering the cgroup hook or BPF_PROG_TEST_RUN; no race or victim-dependent state is required to reach the mismatched-storage OOB path.
- PR:LPrivileges required, low
- Reaching the buggy compatibility check needs only local BPF privileges (CAP_BPF or unprivileged BPF where enabled) plus cgroup attach/test-run access obtainable by unprivileged users in delegated cgroups or user namespaces, not init-namespace root.
- UI:NUser interaction, none
- The attacker loads, wires, and triggers the malicious BPF program chain itself (e.g., creating a socket or using BPF_PROG_TEST_RUN); no action by another user or administrator is required.
- S:UScope, unchanged
- The out-of-bounds cgroup local storage access corrupts kernel heap memory within the same kernel security domain and enables local privilege escalation, not a cross-boundary VM, IOMMU, or sandbox escape.
- C:HConfidentiality impact, high
- Tail-called program C obtains a pointer from bpf_get_local_storage() backed by entry program A's smaller cgroup storage while verifier-approved helpers perform larger accesses, yielding controllable out-of-bounds kernel heap reads.
- I:HIntegrity impact, high
- The returned cgroup storage pointer is writable map memory, and size-mismatched helper copies (e.g., bpf_map_update_elem/copy_map_value_long) enable controllable out-of-bounds heap writes exploitable for kernel corruption and code execution.
- A:HAvailability impact, high
- The heap out-of-bounds read/write can corrupt adjacent kernel objects and readily trigger kernel oops/panic or denial of service, as demonstrated by the cgroup_storage_oob selftest expecting KASAN reports without the fix.