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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Linux | Linux kernel | 4.4 – < 4.4.182, 4.9 – < 4.9.182, 4.14 – < 4.14.127, 4.19 – < 4.19.52, 5.1 – < 5.1.11 | 4.4.182 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 4.19.37-4 | — |
| Debian 13 | linux | 4.19.37-4 | — |
| Debian 12 | linux | 4.19.37-4 | — |
| Debian 9 | linux | 4.9.168-1+deb9u3 | DSA-4465-1 |
| Debian 8 | linux | 3.16.68-2 | DLA-1823-1 |
| Debian 8 | linux-4.9 | 4.9.168-1+deb9u3~deb8u1 | DLA-1824-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | linux-raspi-realtime | No fix yet | — |
| Ubuntu 22.04 LTS | linux-riscv +2 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-gke +3 | No fix yet | — |
| Ubuntu 18.04 LTS | linux | 4.15.0-54.58 | USN-4041-1 |
| Ubuntu 18.04 LTS | linux-aws | 4.15.0-1043.45 | USN-4041-1 |
| Ubuntu 18.04 LTS | linux-azure | 4.18.0-1023.24~18.04.1 | USN-4041-1 |
| Ubuntu 18.04 LTS | linux-gcp +1 | 4.15.0-1036.38 | USN-4041-1 |
| Ubuntu 18.04 LTS | linux-gcp-edge | 4.18.0-1015.16~18.04.1 | — |
| Ubuntu 18.04 LTS | linux-hwe | 4.18.0-25.26~18.04.1 | USN-4041-1 |
| Ubuntu 18.04 LTS | linux-hwe-edge | 5.0.0-20.21~18.04.1 | — |
| Ubuntu 18.04 LTS | linux-kvm | 4.15.0-1038.38 | USN-4041-1 |
| Ubuntu 18.04 LTS | linux-oem | 4.15.0-1045.50 | USN-4041-1 |
| Ubuntu 18.04 LTS | linux-oracle | 4.15.0-1017.19 | USN-4041-1 |
| Ubuntu 18.04 LTS | linux-raspi2 | 4.15.0-1040.43 | USN-4041-1 |
| Ubuntu 18.04 LTS | linux-snapdragon | 4.15.0-1057.62 | USN-4041-1 |
| Ubuntu 16.04 LTS | linux | 4.4.0-154.181 | USN-4041-1 |
| Ubuntu 16.04 LTS | linux-aws | 4.4.0-1087.98 | USN-4041-1 |
| Ubuntu 16.04 LTS | linux-aws-hwe | 4.15.0-1043.45~16.04.1 | USN-4041-1 |
| Ubuntu 16.04 LTS | linux-azure | 4.15.0-1049.54 | USN-4041-1 |
| Ubuntu 16.04 LTS | linux-gcp | 4.15.0-1036.38~16.04.1 | USN-4041-1 |
| Ubuntu 16.04 LTS | linux-hwe | 4.15.0-54.58~16.04.1 | USN-4041-1 |
| Ubuntu 16.04 LTS | linux-kvm | 4.4.0-1051.58 | USN-4041-1 |
| Ubuntu 16.04 LTS | linux-oracle | 4.15.0-1017.19~16.04.2 | USN-4041-1 |
| Ubuntu 16.04 LTS | linux-raspi2 | 4.4.0-1114.123 | USN-4041-1 |
| Ubuntu 16.04 LTS | linux-snapdragon | 4.4.0-1118.124 | USN-4041-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro FIPS-updates 16.04 LTS | linux-fips | 4.4.0-1013.17 | — |
| Ubuntu Pro 20.04 LTS | linux-azure-fde-5.15 | No fix yet | — |
| Ubuntu Pro 14.04 LTS | linux | No fix yet | — |
| Ubuntu Pro 14.04 LTS | linux-aws | 4.4.0-1054.58 | USN-4041-2 |
| Ubuntu Pro 14.04 LTS | linux-azure | 4.15.0-1059.64~14.04.1 | USN-4041-2 |
| Ubuntu Pro 14.04 LTS | linux-lts-xenial | 4.4.0-164.192~14.04.1 | USN-4041-2 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | kernel-rt +12 | 4.18.0-80.4.2.rt9.152.el8_0 | RHSA-2019:1480 |
| RHEL 8 | perf +26 | 4.18.0-80.4.2.el8_0 | RHSA-2019:1479 |
| RHEL 7 | kernel-alt | 4.14.0-115.8.2.el7a | RHSA-2019:1602 |
| RHEL 7 | kernel-rt +10 | 3.10.0-957.21.3.rt56.935.el7 | RHSA-2019:1486 |
| RHEL 7 | perf +18 | 3.10.0-957.21.3.el7 | RHSA-2019:1602, RHSA-2019:1481 |
| RHEL 7 | redhat-release-virtualization-host +2 | 4.2-11.1.el7 | RHSA-2019:1699, RHSA-2019:1594 |
| RHEL 7 | redhat-virtualization-host +1 | 4.2-20190618.0.el7_6 | RHSA-2019:1699, RHSA-2019:1594 |
| RHEL 6 | perf +15 | 2.6.32-754.15.3.el6 | RHSA-2019:1488 |
Show 11 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 7.5 EUS | perf +17 | 3.10.0-862.34.2.el7 | RHSA-2019:1482 |
| RHEL 7.4 EUS | perf +17 | 3.10.0-693.50.3.el7 | RHSA-2019:1483 |
| RHEL 7.3 TUS | perf +11 | 3.10.0-514.66.2.el7 | RHSA-2019:1484 |
| RHEL 7.3 E4S | perf +13 | 3.10.0-514.66.2.el7 | RHSA-2019:1484 |
| RHEL 7.3 AUS | perf +11 | 3.10.0-514.66.2.el7 | RHSA-2019:1484 |
| RHEL 7.2 TUS | perf +11 | 3.10.0-327.79.2.el7 | RHSA-2019:1485 |
| RHEL 7.2 E4S | perf +11 | 3.10.0-327.79.2.el7 | RHSA-2019:1485 |
| RHEL 7.2 AUS | perf +11 | 3.10.0-327.79.2.el7 | RHSA-2019:1485 |
| RHEL 6.6 AUS | perf +9 | 2.6.32-504.79.3.el6 | RHSA-2019:1489 |
| RHEL 6.5 AUS | perf +9 | 2.6.32-431.95.3.el6 | RHSA-2019:1490 |
| Red Hat MRG 2 | kernel-rt +10 | 1:3.10.0-693.50.3.rt56.644.el6rt | RHSA-2019:1487 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP1 | kernel-docs +5 | 4.12.14-197.4.1 | SUSE-SU-2019:1550-1 |
| SLES 15 | kernel-azure +2 | 4.12.14-5.30.1 | SUSE-SU-2019:1535-1 |
| SLES 15 | kernel-docs +6 | 4.12.14-150.22.1 | SUSE-SU-2019:1529-1 |
| SLES 12 SP4 | kernel-azure +2 | 4.12.14-6.15.2 | SUSE-SU-2019:1536-1 |
| SLES 12 SP4 | kernel-docs +4 | 4.12.14-95.19.1 | SUSE-SU-2019:1530-1 |
| SLES 12 SP3 | kernel-azure +2 | 4.4.180-4.31.1 | SUSE-SU-2019:1527-1 |
| SLES 12 SP3 | kernel-docs +4 | 4.4.180-94.97.1 | SUSE-SU-2019:1532-1 |
| SLES 12 SP2 | kernel-syms +2 | 4.4.121-92.114.1 | SUSE-SU-2019:1534-1 |
| SLES 12 SP2 | kgraft-patch-SLE12-SP2_Update_30 | 1-3.5.1 | SUSE-SU-2019:1534-1 |
Show 15 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP1 | kernel-xen +3 | 3.12.74-60.64.115.1 | SUSE-SU-2019:1533-1 |
| SLES 12 SP1 | kgraft-patch-SLE12-SP1_Update_34 | 1-2.5.1 | SUSE-SU-2019:1533-1 |
| SLES 12 | kernel-ec2 +4 | 3.12.61-52.154.1 | SUSE-SU-2019:1692-1, SUSE-SU-2019:1533-1 |
| SLES 12 | kgraft-patch-SLE12_Update_40 | 1-1.5.1 | SUSE-SU-2019:1692-1 |
| SLES 11 SP4 | kernel-ec2 +6 | 3.0.101-108.95.2 | SUSE-SU-2019:14089-1 |
| SLES 11 SP4 | kernel-syms +1 | 3.0.101-108.95.1 | SUSE-SU-2019:14089-1 |
| SLES for SAP 12 SP4 | kernel-azure +2 | 4.12.14-6.15.2 | SUSE-SU-2019:1536-1 |
| SLES for SAP 12 SP4 | kernel-syms +2 | 4.12.14-95.19.1 | SUSE-SU-2019:1530-1 |
| SLES for SAP 12 SP3 | kernel-azure +2 | 4.4.180-4.31.1 | SUSE-SU-2019:1527-1 |
| SLES for SAP 12 SP3 | kernel-syms +2 | 4.4.180-94.97.1 | SUSE-SU-2019:1532-1 |
| SLES for SAP 12 SP2 | kernel-syms +2 | 4.4.121-92.114.1 | SUSE-SU-2019:1534-1 |
| SLES for SAP 12 SP2 | kgraft-patch-SLE12-SP2_Update_30 | 1-3.5.1 | SUSE-SU-2019:1534-1 |
| SLES for SAP 12 SP1 | kernel-xen +3 | 3.12.74-60.64.115.1 | SUSE-SU-2019:1533-1 |
| SLES for SAP 12 SP1 | kgraft-patch-SLE12-SP1_Update_34 | 1-2.5.1 | SUSE-SU-2019:1533-1 |
| SLE Real Time 12 SP4 | kernel-rt +3 | 4.12.14-8.6.1 | SUSE-SU-2019:2756-1 |
| SLE Live Patching 15 SP1 | kernel-default | 4.12.14-197.4.1 | SUSE-SU-2019:1550-1 |
| SLE Live Patching 15 SP1 | kernel-livepatch-SLE15-SP1_Update_1 | 1-3.3.1 | SUSE-SU-2019:1550-1 |
| SLE Live Patching 15 | kernel-default | 4.12.14-150.22.1 | SUSE-SU-2019:1529-1 |
| SLE Live Patching 15 | kernel-livepatch-SLE15_Update_11 | 1-1.5.1 | SUSE-SU-2019:1529-1 |
| SLE Live Patching 12 SP4 | kgraft-patch-SLE12-SP4_Update_5 | 1-6.3.1 | SUSE-SU-2019:1530-1 |
| SLE Live Patching 12 SP3 | kgraft-patch-SLE12-SP3_Update_26 | 1-4.3.3 | SUSE-SU-2019:1532-1 |
| SUSE Real Time Module 15 SP1 | kernel-rt +3 | 4.12.14-14.8.1 | SUSE-SU-2019:2430-1 |
| SUSE OpenStack Cloud 7 | kernel-syms +2 | 4.4.121-92.114.1 | SUSE-SU-2019:1534-1 |
| SUSE OpenStack Cloud 7 | kgraft-patch-SLE12-SP2_Update_30 | 1-3.5.1 | SUSE-SU-2019:1534-1 |
| SUSE Enterprise Storage 4 | kernel-syms +2 | 4.4.121-92.114.1 | SUSE-SU-2019:1534-1 |
| SUSE Enterprise Storage 4 | kgraft-patch-SLE12-SP2_Update_30 | 1-3.5.1 | SUSE-SU-2019:1534-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | kernel-source | 5.14.6-1.4 | openSUSE-SU-2024:13704-1, openSUSE-SU-2024:10728-1 |
| openSUSE Leap 15.1 | kernel-docs +8 | 4.12.14-lp151.28.7.1 | openSUSE-SU-2019:1571-1 |
| openSUSE Leap 15.0 | kernel-docs +8 | 4.12.14-lp150.12.64.1 | openSUSE-SU-2019:1579-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2 | perf +8 | 4.14.123-111.109.amzn2 | ALAS2-2019-1222 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | perf +19 | 4.18.0-80.4.2.el8_0 | ELSA-2019-1479 |
| Oracle Linux 7 | dtrace-modules-3.8.13-118.35.2.el6uek | 0.4.5-3.el6 | ELSA-2019-4686 |
| Oracle Linux 7 | dtrace-modules-3.8.13-118.35.2.el7uek | 0.4.5-3.el7 | ELSA-2019-4686 |
| Oracle Linux 7 | kernel-uek +5 | 3.8.13-118.35.2.el7uek | ELSA-2019-4686, ELSA-2019-4685, ELSA-2019-4684 |
| Oracle Linux 7 | kernel-uek-tools +3 | 4.14.35-1902.2.0.el7uek | ELSA-2019-4685 |
| Oracle Linux 7 | perf +12 | 3.10.0-957.21.3.el7 | ELSA-2019-4685, ELSA-2019-1481 |
Advisories 47
- RHSA-2019:1699 Red Hat Security Advisory: redhat-virtualization-host security and enhancement update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1602 Red Hat Security Advisory: kernel-alt security update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1594 Red Hat Security Advisory: redhat-virtualization-host security update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1490 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1488 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1489 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1486 Red Hat Security Advisory: kernel-rt security update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1487 Red Hat Security Advisory: kernel-rt security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1484 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1485 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1482 Red Hat Security Advisory: kernel security update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1483 Red Hat Security Advisory: kernel security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1480 Red Hat Security Advisory: kernel-rt security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1481 Red Hat Security Advisory: kernel security update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2019:1479 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- USN-4041-1 linux, linux-aws, linux-aws-hwe, linux-azure, linux-gcp, linux-gke-4.15, linux-hwe, linux-kvm, linux-oem, linux-oracle, linux-raspi2, linux-snapdragon update Ubuntu Security Notices (USN) · Apr 22, 2026
- DSA-4465-1 linux - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-1824-1 linux-4.9 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-1823-1 linux - security update Debian Security (DSA / DLA) · Mar 9, 2026
- USN-4041-2 linux-lts-xenial, linux-aws, linux-azure update Ubuntu Security Notices (USN) · Feb 10, 2026
- SUSE-SU-2019:1534-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:14089-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:2756-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:1536-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:1532-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:1535-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:13704-1 kernel-devel-longterm-6.6.17-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:1527-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2019:1571-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2019:1579-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:1550-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:1692-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:1529-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:2430-1 Security update for kernel-source-rt SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10728-1 kernel-devel-5.14.6-1.4 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:1530-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:1533-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Feb 4, 2026
- SSA-462066 SSA-462066: Vulnerability known as TCP SACK PANIC in Industrial Products Siemens ProductCERT · Apr 11, 2023
- WID-SEC-2023-0507 Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service BSI CERT-Bund (WID) · Apr 10, 2023
- ICSA-19-253-03 ICSA-19-253-03_Siemens Industrial Products (Update P) CISA ICS & IT advisories · May 12, 2022
- ICSMA-20-170-06 BD Alaris PCU (Update A) CISA ICS & IT advisories · Jun 23, 2020
- ELSA-2019-1479 Important: kernel security and bug fix update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Jul 30, 2019
- ELSA-2019-1481 Important: kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Jun 18, 2019
- ALAS2-2019-1222 Critical: kernel security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Jun 17, 2019
- ELSA-2019-4685 Important: Unbreakable Enterprise kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Jun 17, 2019
- ELSA-2019-4686 Important: Unbreakable Enterprise kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Jun 17, 2019
- ELSA-2019-4684 Important: Unbreakable Enterprise kernel security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Jun 17, 2019
References
- 108818 vdb-entry
- VU#905115 third-party-advisory
- RHSA-2019:1594 vendor-advisory
- RHSA-2019:1602 vendor-advisory
- [oss-security] 20190628 Re: linux-distros membership application - Microsoft mailing-list
- USN-4041-2 vendor-advisory
- [oss-security] 20190706 Re: linux-distros membership application - Microsoft mailing-list
- [oss-security] 20190706 Re: linux-distros membership application - Microsoft mailing-list
- RHSA-2019:1699 vendor-advisory
- USN-4041-1 vendor-advisory
- https://www.oracle.com/security-alerts/cpujan2020.html
- https://www.oracle.com/security-alerts/cpuoct2020.html
- https://github.com/Netflix/security-bulletins/blob/master/advisories/third-party/2019-001.md
- https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/SACKPanic
- https://access.redhat.com/security/vulnerabilities/tcpsack
- https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA44193
- https://www.synology.com/security/advisory/Synology_SA_19_28
- https://security.netapp.com/advisory/ntap-20190625-0001/
- https://kc.mcafee.com/corporate/index?page=content&id=SB10287
- https://cert-portal.siemens.com/productcert/pdf/ssa-462066.pdf
- https://www.us-cert.gov/ics/advisories/icsa-19-253-03
- http://www.arubanetworks.com/assets/alert/ARUBA-PSA-2020-010.txt
- https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=5f3e2bf008c2221478101ee72f5cb4654b9fc363
- https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=967c05aee439e6e5d7d805e195b3a20ef5c433d6
- https://support.f5.com/csp/article/K35421172
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2019-0008
- https://support.f5.com/csp/article/K35421172?utm_source=f5support&%3Butm_medium=RSS
- https://www.us-cert.gov/ics/advisories/icsma-20-170-06