CVE-2019-11479

CVE-2019-11479 is a high-severity vulnerability in F5 Big-ip Advanced Firewall Manager with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 92% places it in the 100th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-770.

Key facts

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.

Frequently asked questions

What is CVE-2019-11479?
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.
How severe is CVE-2019-11479?
CVE-2019-11479 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2019-11479 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 92% (100th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-11479?
CVE-2019-11479 primarily affects F5 Big-ip Advanced Firewall Manager. In total, 25 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-11479?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2019-11479 published?
CVE-2019-11479 was published on 2019-06-19 and last updated on 2026-06-17.

References

Affected products (25)

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