CVE-2025-40074
Description
From CVE.org
In the Linux kernel, the following vulnerability has been resolved: ipv4: start using dst_dev_rcu() Change icmpv4_xrlim_allow(), ip_defrag() to prevent possible UAF. Change ipmr_prepare_xmit(), ipmr_queue_fwd_xmit(), ip_mr_output(), ipv4_neigh_lookup() to use lockdep enabled dst_dev_rcu().
Statement
The patch replaces non-RCU-safe dst_dev() usages with dst_dev_rcu() and wraps lookups with proper rcu_read_lock(). Without this, concurrency with route/device teardown could yield a dangling dst->dev and a kernel use-after-free, crashing the host. Remote packets can reach these code paths (ICMP, IPv4 defrag, multicast), but a practical trigger typically requires concurrent routing/device changes on the host (admin action), hence for the CVSS the AC:H and most likely DoS-only impact. This issue cannot be reliably triggered by sending crafted packets alone — successful exploitation requires concurrent privileged/server-side actions (e.g. route/interface removal, driver unbind or network-namespace teardown) that change or free the dst->dev while packet processing is underway. A purely unprivileged remote actor cannot force those conditions on a correctly configured system. Triggering this issue in practice typically requires server-side conditions — for example concurrent route/interface changes, netns teardown, or device removal — to occur while packets are being processed. This makes reliable exploitation difficult and confines the risk mainly to DoS. Remote exploitation with a single packet without privileged actions on the host is not expected.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.4 | N/A | 9.8 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | High |
| Integrity Impact | Low | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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