CVE-2019-11479
CVE-2019-11479
In short
The Linux kernel uses a very small default TCP packet size (48 bytes) that allows remote attackers to fragment data transfers excessively, potentially overwhelming the system and causing it to become unresponsive.
Technical detail
CVE-2019-11479 exploits a hardcoded MSS (Maximum Segment Size) default of 48 bytes in the Linux kernel TCP stack, allowing a remote attacker to trigger excessive fragmentation of TCP retransmission queues. This results in increased memory consumption and CPU usage on the target system, leading to denial of service conditions without requiring authentication or local access.
Summary generated and translated by AI from the official description.
Jonathan Looney discovered that the Linux kernel default MSS is hard-coded to 48 bytes. This allows a remote peer to fragment TCP resend queues significantly more than if a larger MSS were enforced. A remote attacker could use this to cause a denial of service. This has been fixed in stable kernel releases 4.4.182, 4.9.182, 4.14.127, 4.19.52, 5.1.11, and is fixed in commits 967c05aee439e6e5d7d805e195b3a20ef5c433d6 and 5f3e2bf008c2221478101ee72f5cb4654b9fc363.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Affected products
Linux · Linux kernelWant to know if your infrastructure is exposed to this?
Talk to TrueHacking →References
https://access.redhat.com/errata/RHSA-2019:1594https://access.redhat.com/errata/RHSA-2019:1602https://access.redhat.com/errata/RHSA-2019:1699https://access.redhat.com/security/vulnerabilities/tcpsackhttps://cert-portal.siemens.com/productcert/pdf/ssa-462066.pdfhttps://github.com/Netflix/security-bulletins/blob/master/advisories/third-party/2019-001.mdhttps://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=5f3e2bf008c2221478101ee72f5cb4654b9fc363https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=967c05aee439e6e5d7d805e195b3a20ef5c433d6https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44193https://kc.mcafee.com/corporate/index?page=content&id=SB10287https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2019-0008https://security.netapp.com/advisory/ntap-20190625-0001/