VulnerabilityPublished 10 Nov 2026

CVE-2026-99288: Linux kernel · inet: reject unhashed sockets during established lookups

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in eb8a2d156f2c1d862fffdfd1b3432bfbcd939879 : patch Linux kernel soon.

Data as of 10 Nov 2026, 18:36 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none

Patch: Available – fixed in eb8a2d156f2c1d862fffdfd1b3432bfbcd939879, d69100340b4cae08d40f898f1b601032403f6be6, 8e5172cbd227fae32f3313cba1f3e1b9edb5c4fd

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to eb8a2d156f2c1d862fffdfd1b3432bfbcd939879, d69100340b4cae08d40f898f1b601032403f6be6 or 8e5172cbd227fae32f3313cba1f3e1b9edb5c4fd.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 079096f103faca2dd87342cca6f23d4b34da8871, < eb8a2d156f2c1d862fffdfd1b3432bfbcd939879	Fixed in eb8a2d156f2c1d862fffdfd1b3432bfbcd939879
LinuxLinux	Affected ≥ 079096f103faca2dd87342cca6f23d4b34da8871, < d69100340b4cae08d40f898f1b601032403f6be6	Fixed in d69100340b4cae08d40f898f1b601032403f6be6
LinuxLinux	Affected ≥ 079096f103faca2dd87342cca6f23d4b34da8871, < 8e5172cbd227fae32f3313cba1f3e1b9edb5c4fd	Fixed in 8e5172cbd227fae32f3313cba1f3e1b9edb5c4fd
LinuxLinux	Affected =4.4	Fixed in–

AI-suggested

A fix is available and has been applied in the Linux kernel in the commits identified (eb8a2d156f2c1d862fffdfd1b3432bfbcd939879, d69100340b4cae08d40f898f1b601032403f6be6, 8e5172cbd227fae32f3313cba1f3e1b9edb5c4fd). Users and administrators should update to a patched kernel version containing these fixes to mitigate this vulnerability.

Description

A vulnerability in the Linux kernel's inet established socket lookup mechanism could cause a kernel NULL pointer dereference and crash. The flaw arises because the lookup functions do not verify whether a socket object is hashed after acquiring a reference, potentially leading to use of an unhashed socket with a NULL listener pointer. This can result in a kernel panic during TCP packet processing. The issue affects Linux kernel version 4.4 and has been fixed in specific commits.

Impact

Exploitation of this vulnerability can cause a kernel NULL pointer dereference leading to a kernel panic and system crash. This affects system stability and availability but does not directly indicate privilege escalation or data disclosure from the provided data.

Summary

The Linux kernel vulnerability CVE-2026-99288 involves the inet established socket lookup functions (__inet_lookup_established and __inet6_lookup_established) which perform lockless TCP established ehash lookups. These functions acquire a reference to a socket after a tuple match but fail to check if the socket is still hashed. If the socket address is reused for a new socket with the same tuple but unhashed, the lookup may return a reference to this unhashed socket. This leads to a NULL pointer dereference when tcp_v4_rcv reads sk_state through a NULL listener pointer, causing a kernel crash. The fix involves checking if the unhashed socket is still hashed after taking a reference and restarting the lookup if not. Additional fixes ensure proper reference counting for request sockets in SYN cookie and related paths. The vulnerability is resolved in the Linux kernel by commits eb8a2d156f2c1d862fffdfd1b3432bfbcd939879, d69100340b4cae08d40f898f1b601032403f6be6, and 8e5172cbd227fae32f3313cba1f3e1b9edb5c4fd.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Nov 2026, 18:36 UTC

Technical details

References

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