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CVE-2026-53076
bpf: Fix OOB in pcpu_init_value
Published 2026-06-24 (4 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-2026-53076 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 | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| 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 | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.10-1 | Update the kernel and reboot. Fixed in 7.0.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
An out-of-bounds read occurs when copying element from a BPF_MAP_TYPE_CGROUP_STORAGE map to another pcpu map with the same value_size that is not rounded up to 8 bytes. The issue happens when: 1. A CGROUP_STORAGE map is created with value_size not aligned to 8 bytes (e.g., 4 bytes) 2. A pcpu map is created with the same value_size (e.g., 4 bytes) 3. Update element in 2 with data in 1 pcpu_init_value assumes that all sources are rounded up to 8 bytes, and invokes copy_map_value_long to make a data copy, However, the assumption doesn't stand since there are some cases where the source may not be rounded up to 8 bytes, e.g., CGROUP_STORAGE, skb->data. the verifier verifies exactly the size that the source claims, not the size rounded up to 8 bytes by kernel, an OOB happens when the source has only 4 bytes while the copy size(4) is rounded up to 8.
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/hashtab.c
- What this is
- BPF [GENERAL] (Safe Dynamic Programs and Tools)MAINTAINERS section matched on kernel/bpf/ · bpf@vger.kernel.org · Supported
Check it on the machine
grep -wE 'CONFIG_BPF|CONFIG_BPF_SYSCALL' /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 switches
- CONFIG_BPF, CONFIG_BPF_SYSCALL
- 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
- 2026-06-24 (4 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
- 0.12%, higher than 1.5% 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 |
|---|---|---|
| 5.10 | 6.6.141 | e19c5ed9f192 |
| 5.10 | 6.12.91 | e0378419b0e2 |
| 5.10 | 6.18.33 | 6086079e6d1c |
| 5.10 | 7.0.10 | 634a793d0e1c |
| 5.10 | 7.1 | 576afddfee8d |
| 5.4.78 | 0 | 0 |
| 5.9.9 | 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
- The vulnerable path is reached through local `bpf(2)` activity: creating BPF maps, loading a BPF program, and invoking `bpf_map_update_elem()` from that program. It is not directly reachable by remote packets without a local attacker-controlled BPF program already installed.
- AC:LAttack complexity, low
- The trigger is deterministic: use a non-8-byte-aligned value size and pass a verifier-valid source buffer into a per-CPU hash update that previously copied the rounded-up size. No race or attacker-external timing condition is required.
- PR:LPrivileges required, low
- A basic local user can reach the most severe reasonable case on systems where unprivileged BPF is enabled, including via socket-filter BPF and packet data sources; otherwise it requires BPF-related capabilities. Under the required higher-severity rule, this is PR:L rather than PR:H.
- UI:NUser interaction, none
- After the local attacker loads the BPF program and creates the maps, exploitation requires no victim action. The attacker triggers the helper path directly.
- S:UScope, unchanged
- The affected component and impacted resources are within the same kernel security authority. This is not a VM escape, IOMMU bypass, or cross-scope boundary violation.
- C:HConfidentiality impact, high
- The bug is an out-of-bounds kernel read whose extra bytes are copied into per-CPU map padding that can be returned through per-CPU map lookup paths. Even though each read is small, repeated attacker-controlled executions can disclose kernel memory, so the higher severity confidentiality value is warranted.
- I:NIntegrity impact, none
- The faulty copy writes only into the destination per-CPU map slot's allocated rounded padding, not past the allocated destination or into security-relevant map value bytes. I found no path turning this into attacker-controlled kernel data modification or control-flow corruption.
- A:HAvailability impact, high
- The reported reproducer is a KASAN slab-out-of-bounds read in a deterministic BPF helper path, and such reachable kernel OOB reads can oops or panic on hardened/sanitized or unlucky layouts. Following the kernel scoring guidance and higher-severity rule, availability is H.