CVE-2019-25045
Description
A use-after-free flaw was found in the Linux kernel’s XFRM subsystem when flushing the XFRM tunnel. This flaw allows a local user to crash the system or possibly escalate their privileges on the system. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.
Statement
This flaw is rated as having a Moderate impact because in the default configuration, the issue can only be triggered by a privileged local user.
For the all versions of the Red Hat Enterprise Linux 8 the fix already applied, so not affected.
For the Red Hat Enterprise Linux 7 the vulnerability not actual too, and it is known that XFRM subsystem vulnerabilities requires CAP_NET_ADMIN capability.
In order to exploit this issue the attacker needs CAP_NET_ADMIN capability, which needs to be granted especially by the administrator to the attacker's process. This in turn requires granting CAP_NET_ADMIN capability to the process' binary and/or attacker's account.
Another possibility to obtain CAP_NET_ADMIN capability in Red Hat Enterprise Linux 7 for an attacker is running a process inside a user+network namespace with mapped root privileges inside the namespace. Since Red Hat Enterprise Linux 7 does not have unprivileged user namespaces enabled by default, local or remote unprivileged users also cannot abuse namespaces to grant this capability to themselves and elevate their privileges.
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 | 7.8 | 7.8 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD: 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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