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Fencer Vulns
high 7.5

CVE-2025-38525 json

rxrpc: Fix irq-disabled in local_bh_enable()

published 2025-08-16 14 mo ago modified 2026-08-10 2 mo ago also EUVD-2025-27884

cvss
7.5
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 35%
public exploits
0
none known

Summary

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

rxrpc: Fix irq-disabled in local_bh_enable()

The rxrpc_assess_MTU_size() function calls down into the IP layer to find out the MTU size for a route. When accepting an incoming call, this is called from rxrpc_new_incoming_call() which holds interrupts disabled across the code that calls down to it. Unfortunately, the IP layer uses local_bh_enable() which, config dependent, throws a warning if IRQs are enabled:

WARNING: CPU: 1 PID: 5544 at kernel/softirq.c:387 __local_bh_enable_ip+0x43/0xd0 ... RIP: 0010:__local_bh_enable_ip+0x43/0xd0 ... Call Trace: <TASK> rt_cache_route+0x7e/0xa0 rt_set_nexthop.isra.0+0x3b3/0x3f0 __mkroute_output+0x43a/0x460 ip_route_output_key_hash+0xf7/0x140 ip_route_output_flow+0x1b/0x90 rxrpc_assess_MTU_size.isra.0+0x2a0/0x590 rxrpc_new_incoming_peer+0x46/0x120 rxrpc_alloc_incoming_call+0x1b1/0x400 rxrpc_new_incoming_call+0x1da/0x5e0 rxrpc_input_packet+0x827/0x900 rxrpc_io_thread+0x403/0xb60 kthread+0x2f7/0x310 ret_from_fork+0x2a/0x230 ret_from_fork_asm+0x1a/0x30 ... hardirqs last enabled at (23): _raw_spin_unlock_irq+0x24/0x50 hardirqs last disabled at (24): _raw_read_lock_irq+0x17/0x70 softirqs last enabled at (0): copy_process+0xc61/0x2730 softirqs last disabled at (25): rt_add_uncached_list+0x3c/0x90

Fix this by moving the call to rxrpc_assess_MTU_size() out of rxrpc_init_peer() and further up the stack where it can be done without interrupts disabled.

It shouldn't be a problem for rxrpc_new_incoming_call() to do it after the locks are dropped as pmtud is going to be performed by the I/O thread - and we're in the I/O thread at this point.

Patch / fix

  • Linux Linux 6.6.151, 6.12.103, 6.15.8, 6.16
  • linux Debian 13 6.12.105-1
  • linux-6.12 Debian 12 6.12.107-1~deb12u1

debian advisories DEBIAN-CVE-2025-38525

  • linux-aws-6.14 Ubuntu 24.04 LTS 6.14.0-1017.17~24.04.1
  • linux-gcp-6.14 Ubuntu 24.04 LTS 6.14.0-1020.21~24.04.1
  • linux-oem-6.14 Ubuntu 24.04 LTS 6.14.0-1016.16
  • linux-azure-6.14 Ubuntu 24.04 LTS 6.14.0-1017.17~24.04.1
  • linux-riscv-6.14 Ubuntu 24.04 LTS 6.14.0-36.36.1~24.04.1
  • linux-oracle-6.14 Ubuntu 24.04 LTS 6.14.0-1017.17~24.04.1
  • linux-realtime-6.14 Ubuntu Pro Realtime 24.04 LTS 6.14.0-1016.16~24.04.1

ubuntu advisories UBUNTU-CVE-2025-38525

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

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-2025-38525 updated cvss 4.4

kernel: rxrpc: Fix irq-disabled in local_bh_enable()

  • Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix planned “No mitigation is currently available that meets Red Hat Product Security’s standards for usability, deployment, applicability, or stability.”
  • 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

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

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.