critical 9.1

CVE-2026-31636 in the critical feed json

rxrpc: fix RESPONSE authenticator parser OOB read

published 2026-04-24 6 mo ago modified 2026-08-05 3 mo ago also EUVD-2026-25529

cvss: 9.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits: 0; none known

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

rxgk_verify_authenticator() copies auth_len bytes into a temporary buffer and then passes p + auth_len as the parser limit to rxgk_do_verify_authenticator(). Since p is a __be32 *, that inflates the parser end pointer by a factor of four and lets malformed RESPONSE authenticators read past the kmalloc() buffer.

Decoded from the original latest-net reproduction logs with scripts/decode_stacktrace.sh:

BUG: KASAN: slab-out-of-bounds in rxgk_verify_response() Call Trace: dump_stack_lvl() [lib/dump_stack.c:123] print_report() [mm/kasan/report.c:379 mm/kasan/report.c:482] kasan_report() [mm/kasan/report.c:597] rxgk_verify_response() [net/rxrpc/rxgk.c:1103 net/rxrpc/rxgk.c:1167 net/rxrpc/rxgk.c:1274] rxrpc_process_connection() [net/rxrpc/conn_event.c:266 net/rxrpc/conn_event.c:364 net/rxrpc/conn_event.c:386] process_one_work() [kernel/workqueue.c:3281] worker_thread() [kernel/workqueue.c:3353 kernel/workqueue.c:3440] kthread() [kernel/kthread.c:436] ret_from_fork() [arch/x86/kernel/process.c:164]

Allocated by task 54: rxgk_verify_response() [include/linux/slab.h:954 net/rxrpc/rxgk.c:1155 net/rxrpc/rxgk.c:1274] rxrpc_process_connection() [net/rxrpc/conn_event.c:266 net/rxrpc/conn_event.c:364 net/rxrpc/conn_event.c:386]

Convert the byte count to __be32 units before constructing the parser limit.

Patch / fix

fixed in 1 distros 5 links 3

Linux Linux 6.18.23, 6.19.13, 7.0

debian ubuntu red hat almalinux rocky linux

linux Debian 14 6.19.13-1

debian advisories DEBIAN-CVE-2026-31636

linux-nvidia Ubuntu 26.04 LTS 7.0.0-1006.6
linux-gcp-6.17 Ubuntu 24.04 LTS 6.17.0-1022.25
linux-hwe-6.17 Ubuntu 24.04 LTS 6.17.0-42.42
linux-oem-6.17 Ubuntu 24.04 LTS 6.17.0-1032.32
linux-azure-6.17 Ubuntu 24.04 LTS 6.17.0-1022.22
linux-nvidia-6.17 Ubuntu 24.04 LTS 6.17.0-1031.31
linux-oracle-6.17 Ubuntu 24.04 LTS 6.17.0-1020.20
linux-realtime-6.17 Ubuntu Pro Realtime 24.04 LTS 6.17.0-1019.22

ubuntu advisories UBUNTU-CVE-2026-31636

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 RHEL 10.2 6.12.0-211.28.1.el10_2
rv RHEL 10.2 6.12.0-211.28.1.el10_2
perf RHEL 10.2 6.12.0-211.28.1.el10_2
rtla RHEL 10.2 6.12.0-211.28.1.el10_2
libperf RHEL 10.2 6.12.0-211.28.1.el10_2
kernel-rt RHEL 10.2 6.12.0-211.28.1.el10_2
kernel-64k RHEL 10.2 6.12.0-211.28.1.el10_2
kernel-core RHEL 10.2 6.12.0-211.28.1.el10_2

red hat advisories RHSA-2026:30129

kernel AlmaLinux 10 6.12.0-211.28.1.el10_2
rv AlmaLinux 10 6.12.0-211.28.1.el10_2
perf AlmaLinux 10 6.12.0-211.28.1.el10_2
rtla AlmaLinux 10 6.12.0-211.28.1.el10_2
libperf AlmaLinux 10 6.12.0-211.28.1.el10_2
kernel-rt AlmaLinux 10 6.12.0-211.28.1.el10_2
kernel-64k AlmaLinux 10 6.12.0-211.28.1.el10_2
kernel-core AlmaLinux 10 6.12.0-211.28.1.el10_2

almalinux advisories ALSA-2026:30129

kernel Rocky Linux 10 6.12.0-211.28.1.el10_2

rocky linux advisories RLSA-2026:30129

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-2026-31636 updated 2026-11-07 cvss 7.1

kernel: rxrpc: fix RESPONSE authenticator parser OOB read

Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.28.1.el10_2, perf 6.12.0-211.28.1.el10_2, rtla 6.12.0-211.28.1.el10_2, python3-perf 6.12.0-211.28.1.el10_2, kernel-devel-matched 6.12.0-211.28.1.el10_2, kernel-64k-devel-matched 6.12.0-211.28.1.el10_2, +7 more Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.28.1.el10_2, kernel-64k 6.12.0-211.28.1.el10_2, kernel-core 6.12.0-211.28.1.el10_2, kernel-tools 6.12.0-211.28.1.el10_2, kernel-modules 6.12.0-211.28.1.el10_2, kernel-64k-core 6.12.0-211.28.1.el10_2, +28 more Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.28.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.28.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.28.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.28.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.28.1.el10_2 Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.28.1.el10_2, kernel-rt-64k 6.12.0-211.28.1.el10_2, kernel-rt-core 6.12.0-211.28.1.el10_2, kernel-rt-modules 6.12.0-211.28.1.el10_2, kernel-rt-64k-core 6.12.0-211.28.1.el10_2, kernel-rt-debug-core 6.12.0-211.28.1.el10_2, +14 more Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.28.1.el10_2, kernel-rt-core 6.12.0-211.28.1.el10_2, kernel-rt-modules 6.12.0-211.28.1.el10_2, kernel-rt-debug-core 6.12.0-211.28.1.el10_2, kernel-rt-modules-core 6.12.0-211.28.1.el10_2, kernel-rt-debug-modules 6.12.0-211.28.1.el10_2, +4 more
fixed: vendor fix RHSA-2026:30129
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 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
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

Exploit prediction

0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	9.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected products

Linux Linux

Classification

Weakness

CWE-125 Out-of-bounds Read

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2026-31636
NVD CVE-2026-31636

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary