CVE-2019-11477

Impact:
Important
Public Date:
2019-06-17
Bugzilla:
1719123: CVE-2019-11477 Kernel: tcp: integer overflow while processing SACK blocks allows remote denial of service
An integer overflow flaw was found in the way the Linux kernel's networking subsystem processed TCP Selective Acknowledgment (SACK) segments. While processing SACK segments, the Linux kernel's socket buffer (SKB) data structure becomes fragmented. Each fragment is about TCP maximum segment size (MSS) bytes. To efficiently process SACK blocks, the Linux kernel merges multiple fragmented SKBs into one, potentially overflowing the variable holding the number of segments. A remote attacker could use this flaw to crash the Linux kernel by sending a crafted sequence of SACK segments on a TCP connection with small value of TCP MSS, resulting in a denial of service (DoS).

Find out more about CVE-2019-11477 from the MITRE CVE dictionary dictionary and NIST NVD.

Statement

Red Hat Product Security is aware of this issue. Updates will be released as they become available. For additional information, please refer to the Red Hat Knowledgebase article: https://access.redhat.com/security/vulnerabilities/tcpsack

CVSS v3 metrics

CVSS3 Base Score 7.5
CVSS3 Base Metrics CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity Impact None
Availability Impact High

Red Hat Security Errata

Platform Errata Release Date
Red Hat Enterprise Linux for Real Time for NFV (v. 7) (kernel-rt) RHSA-2019:1486 2019-06-17
Red Hat Enterprise Linux Update Services for SAP Solutions 7.3 (kernel) RHSA-2019:1484 2019-06-17
Red Hat Enterprise Linux Extended Update Support 7.5 (kernel) RHSA-2019:1482 2019-06-17
Red Hat Enterprise Linux 8 (kernel) RHSA-2019:1479 2019-06-17
Red Hat Enterprise Linux Advanced Update Support 7.3 (kernel) RHSA-2019:1484 2019-06-17
Red Hat Enterprise Linux 7.3 Telco Extended Update Support (kernel) RHSA-2019:1484 2019-06-17
Red Hat Enterprise Linux Advanced Update Support 7.2 (kernel) RHSA-2019:1485 2019-06-17
Red Hat Enterprise Linux 8 (kernel) RHSA-2019:1479 2019-06-17
Red Hat MRG Grid for RHEL 6 Server v.2 (kernel-rt) RHSA-2019:1487 2019-06-17
Red Hat Enterprise Linux 6 (kernel) RHSA-2019:1488 2019-06-17
Red Hat Enterprise Linux 7 (kernel) RHSA-2019:1481 2019-06-17
Red Hat Enterprise Linux Advanced Update Support 6.6 (kernel) RHSA-2019:1489 2019-06-17
Red Hat Enterprise Linux 8 (kernel-rt) RHSA-2019:1480 2019-06-17
Red Hat Virtualization 4 Management Agent for RHEL 7 Hosts (redhat-virtualization-host) RHSA-2019:1594 2019-06-25
Red Hat Enterprise Linux 7 (kernel-alt) RHSA-2019:1602 2019-06-25
Red Hat Enterprise Linux Extended Update Support 7.4 (kernel) RHSA-2019:1483 2019-06-17
Red Hat Enterprise Linux Server Update Services for SAP Solutions 7.2 (kernel) RHSA-2019:1485 2019-06-17
Red Hat Enterprise Linux 8 (kernel-rt) RHSA-2019:1480 2019-06-17
Red Hat Virtualization 4 Management Agent for RHEL 7 Hosts (redhat-virtualization-host) RHSA-2019:1699 2019-07-08
Red Hat Enterprise Linux Advanced Update Support 6.5 (kernel) RHSA-2019:1490 2019-06-17
Red Hat Enterprise Linux Server TUS (v. 7.2) (kernel) RHSA-2019:1485 2019-06-17

Affected Packages State

Platform Package State
Red Hat OpenShift Container Platform 4.1 kernel Not affected
Red Hat Enterprise Linux 5 kernel Not affected
Unless explicitly stated as not affected, all previous versions of packages in any minor update stream of a product listed here should be assumed vulnerable, although may not have been subject to full analysis.

Acknowledgements

Red Hat would like to thank Jonathan Looney (Netflix Information Security) for reporting this issue.

Mitigation

For mitigation, please refer to the Red Hat Knowledgebase article: https://access.redhat.com/security/vulnerabilities/tcpsack

External References

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