CVE-2026-98383
Description
A flaw was found in the Linux kernel's BPF (Berkeley Packet Filter) subsystem. A local attacker with privileges to load BPF programs could exploit this vulnerability to cause a Denial of Service (DoS) or potentially corrupt system memory. The issue occurs when an IPv6 segment routing program modifies routing headers and subsequently triggers packet buffer reallocation, leaving an internal pointer referencing invalid memory. Subsequent validation routines write through this dangling pointer, resulting in memory corruption and a system crash.
Statement
An LWT_SEG6LOCAL BPF program can invalidate its cached SRH with bpf_lwt_seg6_adjust_srh() and then call bpf_skb_pull_data(), which may reallocate skb head and leave the per CPU SRH pointer dangling. Post program SRH validation can then write through the stale pointer, creating a write after free style memory corruption primitive in the host kernel. For the CVSS the PR:L value is used for the paranoid score because a reduced capability container root or service with delegated BPF and network administration capabilities may be able to load and attach the required program without full host root privileges. This is not directly network reachable because remote packets cannot install the unsafe BPF program, although packets can execute it after local configuration. Impact is at least a local denial of service and may include privilege escalation or host kernel compromise if the stale write can be shaped reliably.
Mitigation
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
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 | 5.5 | N/A | 7.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | None | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/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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