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CVE-2026-74403
crypto: ccp - Check for page allocation failure correctly in TIO
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/crypto. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-74403 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| 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
Sashiko notes: > if __snp_alloc_firmware_pages() returns NULL under memory pressure, is it > safe to pass it directly to page_address()? > > On architectures without HASHED_PAGE_VIRTUAL, page_address(NULL) might > compute a deterministic but invalid, non-zero virtual address. The > subsequent if (tio_status) check would then evaluate to true, and > sev_tsm_init_locked() would dereference the invalid pointer. Indeed, page_address(NULL) will return non-NULL garbage here. Fix this by checking the page allocation itself for NULL, not the resulting virtual address.
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.
drivers/crypto/ccp/sev-dev.c
- What this is
- AMD CRYPTOGRAPHIC COPROCESSOR (CCP) DRIVER - SEV SUPPORTMAINTAINERS section matched on drivers/crypto/ccp/sev* · linux-crypto@vger.kernel.org · Supported
- Kernel module
- ccp
Check it on the machine
grep -wE 'CONFIG_CRYPTO|CONFIG_CRYPTO_DEV_CCP|CONFIG_CRYPTO_DEV_CCP_DD|CONFIG_CRYPTO_DEV_SP_PSP' /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 ccpPrints 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/arm64, arm64/cloud-arm64, arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, i386/686, i386/686-pae, i386/rt/686-pae, ppc64el/powerpc64le
- trixieMnot built on amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_CRYPTO, CONFIG_CRYPTO_DEV_CCP, CONFIG_CRYPTO_DEV_CCP_DD, CONFIG_CRYPTO_DEV_SP_PSP
- 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
- 2026-08-15 (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
- 0.17%, higher than 5.4% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/crypto
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.19 | 7.1.5 | 17e1aae19a06 |
| 6.19 | 7.2 | a8d5370eef00 |
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 flaw is in __sev_snp_init_locked() reached only through sev_platform_init() via KVM_SEV_INIT/KVM_SEV_INIT2 ioctls on /dev/kvm or kernel boot init; SEV-TIO platform setup has no network-facing entry point.
- AC:LAttack complexity, low
- An attacker who can trigger first-time SNP init (e.g. psp_init_on_probe=0) can concurrently exhaust host memory to force __snp_alloc_firmware_pages() to return NULL and reliably reach the faulty page_address(NULL) path.
- PR:LPrivileges required, low
- Reaching this code requires opening /dev/kvm and issuing KVM SNP initialization ioctls, which needs CAP_SYS_ADMIN obtainable by an unprivileged user inside a user namespace.
- UI:NUser interaction, none
- Exploitation needs only attacker-initiated KVM ioctls or boot-time SNP initialization; no action by another user or victim is required.
- S:UScope, unchanged
- Impact is confined to the host kernel during SNP-TIO initialization (oops, memory corruption); it does not cross a VM, container, or IOMMU security boundary.
- C:HConfidentiality impact, high
- page_address(NULL) yields a non-NULL direct-map pointer, so sev_tio_init_locked() dereferences invalid memory and passes a bogus physical address to PSP firmware via SEV_CMD_TIO_STATUS, enabling kernel memory disclosure.
- I:HIntegrity impact, high
- The invalid pointer causes unchecked reads/writes in sev_tio_init_locked() and may direct PSP firmware to write TIO status data to an unintended physical page, enabling exploitable memory corruption.
- A:HAvailability impact, high
- Dereferencing the bogus page_address(NULL) result in sev_tsm_init_locked()/sev_tio_init_locked() can trigger a kernel oops or panic, crashing the host during SNP-TIO initialization.