CVE-2026-80844
Description
A flaw was found in the Linux kernel's xfrm subsystem, specifically within the AH6 (Authentication Header for IPv6) module. The ipv6_rearrange_rthdr() function does not properly validate the segments_left field in routing headers when processing raw IPv6 HDRINCL packets. This oversight allows an attacker to craft a malicious packet that can cause an out-of-bounds memory access, potentially leading to memory corruption.
Security Bulletin
Statement
This issue is classified as Important severity because exploitation can be achieved by a local attacker with unprivileged user access. An attack could leverage user namespaces to obtain elevated network permissions within the namespace, then sends specially crafted IPv6 packets with malformed Authentication Header routing headers. Exploitation is challenging but achievable due to complex setup including IPv6 AH/XFRM, ESP-in-UDP encapsulation, and specific timing and memory layout conditions. This memory corruption can enable local privilege escalation to root from an unprivileged user account.
Mitigation
See the security bulletin for a detailed mitigation procedure.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.3 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | High | N/A | N/A |
| Integrity Impact | Low | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability
Technical Impact: Read Memory; Modify Memory; Execute Unauthorized Code or Commands
Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. This can often be used to subvert any other security service.
Availability
Technical Impact: Modify Memory; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU)
Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.
Frequently Asked Questions
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