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CVE-2026-63805
crypto: nx - fix nx_crypto_ctx_exit argument
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem drivers/crypto. Debian urgency: not yet assigned.
Debian does not build this code. The per-release build detail is under "Where it lives" below.
What to do, per Debian release
Debian's own status for CVE-2026-63805 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 | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 7.1.3-1 | Update the kernel and reboot. Fixed in 7.1.3-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.3-1 | Update the kernel and reboot. Fixed in 7.1.3-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
nx_crypto_ctx_shash_exit calls nx_crypto_ctx_exit with crypto_shash_ctx(...) but crypto_shash_ctx gives a nx_crypto_ctx *, not a crypto_tfm *. Fix the type in nx_crypto_ctx_exit and drop the bogus crypto_tfm_ctx call. This fixes the following oops: BUG: Unable to handle kernel data access at 0xc0403effffffffc8 Faulting instruction address: 0xc000000000396cb4 Oops: Kernel access of bad area, sig: 11 [#15] Call Trace: nx_crypto_ctx_shash_exit+0x24/0x60 crypto_shash_exit_tfm+0x28/0x40 crypto_destroy_tfm+0x98/0x140 crypto_exit_ahash_using_shash+0x20/0x40 crypto_destroy_tfm+0x98/0x140 hash_release+0x1c/0x30 alg_sock_destruct+0x38/0x60 __sk_destruct+0x48/0x2b0 af_alg_release+0x58/0xb0 __sock_release+0x68/0x150 sock_close+0x20/0x40 __fput+0x110/0x3a0 sys_close+0x48/0xa0 system_call_exception+0x140/0x2d0 system_call_common+0xf4/0x258 .. which came from hardlink(1) opportunistically using AF_ALG. The same problem exists with nx_crypto_ctx_skcipher_exit getting a context it wasn't expecting, but apparently nobody hit that for years.
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/nx/nx.c
drivers/crypto/nx/nx.h
- What this is
- IBM Power in-Nest Crypto AccelerationMAINTAINERS section matched on drivers/crypto/nx/nx.* · linux-crypto@vger.kernel.org · Supported
- Kernel module
- none to look for. The file would have gone into nx_crypto, and Debian does not compile it into that module, so finding nx_crypto in lsmod would say nothing about this CVE.
Check it on the machine
grep -wE 'CONFIG_CRYPTO|CONFIG_CRYPTO_DEV_NX|CONFIG_CRYPTO_DEV_NX_ENCRYPT' /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 does not build this code. In 4 releases below, every kernel flavour Debian publishes has the switch off, so the vulnerable file is compiled into no kernel binary Debian ships.
- bookworm, trixie, forky, sidn
- n
- not enabled on any flavour - this release does not build the code
- Build switches
- CONFIG_CRYPTO, CONFIG_CRYPTO_DEV_NX, CONFIG_CRYPTO_DEV_NX_ENCRYPT
- 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
- 2026-07-19 (3 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
- 0.13%, higher than 2.6% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- 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 |
|---|---|---|
| 5.5 | 6.18.38 | 8d8507a45766 |
| 5.5 | 7.1.3 | 833033e6e55a |
| 5.5 | 7.2 | 4e67f504ee9d |
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 a local syscall path (socket/AF_ALG bind, then close via sys_close) through the crypto userspace API; the NX driver is not reachable from remote network packet handling.
- AC:LAttack complexity, low
- On affected IBM Power pSeries systems with NX hardware and the nx-crypto driver loaded, an attacker can deterministically trigger the bug by opening an AF_ALG hash socket, binding a SHA algorithm that selects the nx driver, and closing the socket.
- PR:LPrivileges required, low
- No special privileges are required beyond a normal local user account; AF_ALG sockets are available to unprivileged users and remain reachable from user namespaces without init-namespace root.
- UI:NUser interaction, none
- No victim interaction is needed beyond the attacker running their own program that opens and closes an AF_ALG crypto socket (as demonstrated by hardlink(1) opportunistically using AF_ALG).
- S:UScope, unchanged
- Impact is confined to kernel memory within the same security authority; this is a local kernel memory-corruption/crash issue, not a VM escape or cross-security-boundary bypass.
- C:HConfidentiality impact, high
- The type confusion causes reads through a miscomputed context pointer before the fault, and erroneous kfree_sensitive() on attacker-influenced kernel pointers can corrupt heap metadata and enable further information disclosure.
- I:HIntegrity impact, high
- The same type confusion leads to kfree_sensitive() on a wrong address and NULL pointer writes through a misaligned nx_crypto_ctx, giving exploitable heap corruption and arbitrary kernel write primitives.
- A:HAvailability impact, high
- The bug reliably causes a kernel oops (SIGSEGV in kernel mode) during crypto context teardown, crashing the calling context and potentially the entire system under panic-on-oops policy.