Synology-SA-19:28 Linux kernel

Abstract

CVE-2019-11477, CVE-2019-11478 and CVE-2019-11479 allow remote attackers to conduct denial-of-service attacks via a susceptible version of DiskStation Manager (DSM) or Synology Router Manager (SRM).

Affected Products

Mitigation

None

Detail

• CVE-2019-11477

  • Severity: Important
  • CVSS3 Base Score: 7.5
  • CVSS3 Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
  • Jonathan Looney discovered that the TCP_SKB_CB(skb)->tcp_gso_segs value was subject to an integer overflow in the Linux kernel when handling TCP Selective Acknowledgments (SACKs). 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 commit 3b4929f65b0d8249f19a50245cd88ed1a2f78cff.

• CVE-2019-11479

  • Severity: Moderate
  • CVSS3 Base Score: 5.3
  • CVSS3 Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
  • 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.

• CVE-2019-11478

  • Severity: Moderate
  • CVSS3 Base Score: 5.3
  • CVSS3 Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
  • Jonathan Looney discovered that the TCP retransmission queue implementation in tcp_fragment in the Linux kernel could be fragmented when handling certain TCP Selective Acknowledgment (SACK) sequences. 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 commit f070ef2ac66716357066b683fb0baf55f8191a2e.

Reference

• Multiple TCP Selective Acknowledgement (SACK) and Maximum Segment Size (MSS) networking vulnerabilities may cause denial-of-service conditions in Linux and FreeBSD kernels
• CVE-2019-11477
• CVE-2019-11478
• CVE-2019-11479

Revision