CVE-2016-8655
Description
A race condition issue leading to a use-after-free flaw was found in the way the raw packet sockets implementation in the Linux kernel networking subsystem handled synchronization while creating the TPACKET_V3 ring buffer. A local user able to open a raw packet socket (requires the CAP_NET_RAW capability) could use this flaw to elevate their privileges on the system.
Statement
This issue does not affect Red Hat Enterprise Linux 5 and 6.
This issue does affect Red Hat Enterprise Linux 7 and Red Hat Enterprise MRG 2. Future updates for the respective releases will address this issue.
In a default or common use of Red Hat Enterprise Linux 7 this issue does not allow an unprivileged local user elevate their privileges on the system.
In order to exploit this issue the attacker needs CAP_NET_RAW capability, which needs to be granted by the administrator to the attacker's account. Since Red Hat Enterprise Linux 7 does not have unprivileged user namespaces enabled by default, local 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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7 | 7.8 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | 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:3.0/AV:L/AC:H/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
CVSS v2 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.6 | 7.2 | N/A |
| Attack Vector | Local | Local | N/A |
| Access Complexity | Medium | Low | N/A |
| Authentication | Single | None | N/A |
| Confidentiality Impact | Complete | Complete | N/A |
| Integrity Impact | Complete | Complete | N/A |
| Availability Impact | Complete | Complete | N/A |
Vector
Red Hat: AV:L/AC:M/Au:S/C:C/I:C/A:C
NVD: AV:L/AC:L/Au:N/C:C/I:C/A:C
Understanding the Weakness (CWE)
Integrity,Other
Technical Impact: Alter Execution Logic; Unexpected State
The main problem is that -- if a lock is overcome -- data could be altered in a bad state.
Acknowledgements
Red Hat would like to thank Philip Pettersson for reporting this issue.
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