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Fencer Vulns
high 7.1

CVE-2026-74578 json

crypto: algif_skcipher - force synchronous processing on trees without ctx->state

published 2026-08-16 2 mo ago modified 2026-10-16 23 d ago also EUVD-2026-59939

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

crypto: algif_skcipher - force synchronous processing on trees without ctx->state

The AIO/async path in skcipher_recvmsg() passes the socket-wide ctx->iv directly into the skcipher request. After io_submit() the socket lock is dropped and the request is processed asynchronously, so a concurrent sendmsg(ALG_SET_IV) can overwrite ctx->iv and make the in-flight request run under an attacker-controlled IV. For CTR/stream modes this is IV/keystream reuse and lets an unprivileged user recover the plaintext of a concurrent operation.

Snapshotting ctx->iv into per-request storage for the async path is not sufficient. For ciphers with statesize == 0 - which includes cbc and ctr - the MSG_MORE inter-chunk IV chaining is carried solely by the in-place req->iv writeback, which a snapshot redirects into per-request memory that af_alg_free_resources() releases on completion, silently producing wrong output. Writing the IV back from the completion callback instead is not possible either: that would require lock_sock() there, but the callback can run in softirq/atomic context, so it must not sleep.

Make the operation synchronous instead, which removes both the IV race and any writeback race. This is equivalent to the upstream resolution, commit fcc77d33a34c ("net: Remove support for AIO on sockets"), which removed the AIO socket path across net/ entirely and so produces the same end state for this file. This patch deviates from that commit deliberately: rather than removing AIO socket support tree-wide, which would be far too invasive for stable, it removes only the AIO branch in crypto/algif_skcipher.c. io_submit() now completes synchronously; AF_ALG async is rarely used in practice.

The -EIOCBQUEUED check in skcipher_recvmsg() is now dead but harmless, and is left alone to keep the fix minimal.

Tested on 6.6.y: attacker IV injection dropped from 2296/200000 to 0/200000 after the change; MSG_MORE chunked CTR output bit-identical to single-shot.

Patch / fix

  • Linux Linux 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40, 7.1.5, 7.2
  • linux Debian 12 6.1.180-1
  • linux Debian 13 6.12.100-1
  • linux Debian 14 7.1.5-1

debian advisories DEBIAN-CVE-2026-74578

  • linux Ubuntu 22.04 LTS 5.15.0-198.208
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1117.124
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1118.128
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1113.119
  • linux-ibm Ubuntu 22.04 LTS 5.15.0-1111.115
  • linux-kvm Ubuntu 22.04 LTS 5.15.0-1109.114
  • linux-azure Ubuntu 22.04 LTS 5.15.0-1123.132
  • linux-gkeop Ubuntu 22.04 LTS 5.15.0-1100.108

ubuntu advisories UBUNTU-CVE-2026-74578

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-rt Real Time Module 15 SP7 6.4.0-150700.7.81.1
  • kernel-syms-rt Real Time Module 15 SP7 6.4.0-150700.7.81.1
  • kernel-source-rt Real Time Module 15 SP7 6.4.0-150700.7.81.1
  • kernel-rt SLE Micro 5.4 5.14.21-150400.15.192.2
  • kernel-source-rt SLE Micro 5.4 5.14.21-150400.15.192.2
  • kernel-rt SLE Micro 5.5 5.14.21-150500.13.167.2
  • kernel-source-rt SLE Micro 5.5 5.14.21-150500.13.167.2
  • kernel-64kb SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS, SLE High Performance Computing 15 SP4-ESPOS 5.14.21-150400.24.246.1

suse advisories SUSE-SU-2026:4940-1SUSE-SU-2026:4939-1SUSE-SU-2026:4938-1SUSE-SU-2026:4937-1SUSE-SU-2026:4936-1SUSE-SU-2026:4935-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.40.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.40.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.40.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.40.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.40.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.40.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.40.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.40.1

opensuse advisories openSUSE-SU-2026:22167-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-74578 updated cvss 7.0

kernel: crypto: algif_skcipher - force synchronous processing on trees without ctx->state

  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix available
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
23 d ago

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

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