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redhatRedHatRHSA-2016:1939
HistorySep 27, 2016 - 11:08 a.m.

(RHSA-2016:1939) Important: kernel security and bug fix update

2016-09-2711:08:46
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41

4.8 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

LOW

Availability Impact

LOW

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L

5.8 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:M/Au:N/C:N/I:P/A:P

0.004 Low

EPSS

Percentile

74.4%

The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fix(es):

  • It was found that the RFC 5961 challenge ACK rate limiting as implemented in the Linux kernel’s networking subsystem allowed an off-path attacker to leak certain information about a given connection by creating congestion on the global challenge ACK rate limit counter and then measuring the changes by probing packets. An off-path attacker could use this flaw to either terminate TCP connection and/or inject payload into non-secured TCP connection between two endpoints on the network. (CVE-2016-5696, Important)

Red Hat would like to thank Yue Cao (Cyber Security Group of the CS department of University of California in Riverside) for reporting this issue.

Bug Fix(es):

  • Previously, the BUG_ON() signal appeared in the fs_clear_inode() function where the nfs_have_writebacks() function reported a positive value for nfs_inode->npages. As a consequence, a kernel panic occurred. The provided patch performs a serialization by holding the inode i_lock over the check of PagePrivate and locking the request, which fixes this bug. (BZ#1365163)

4.8 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

LOW

Availability Impact

LOW

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L

5.8 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:M/Au:N/C:N/I:P/A:P

0.004 Low

EPSS

Percentile

74.4%