VulnerabilityPublished 18 Oct 2026

CVE-2026-98646: Linux kernel · tcp: Skip cond_resched() in inet_csk_listen_stop() under BPF context

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in ee7246bccb9da66076dd8094daa48bdc761d6b76 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in ee7246bccb9da66076dd8094daa48bdc761d6b76, eaab8cab451b9502ce224cd202550375b894a467, 55bbebf2829c3f47c5a48fc261740301d0f25f48 +2

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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 to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 4ddbcb886268af8d12a23e6640b39d1d9c652b1b, < ee7246bccb9da66076dd8094daa48bdc761d6b76	Fixed in ee7246bccb9da66076dd8094daa48bdc761d6b76
LinuxLinux	Affected ≥ 4ddbcb886268af8d12a23e6640b39d1d9c652b1b, < eaab8cab451b9502ce224cd202550375b894a467	Fixed in eaab8cab451b9502ce224cd202550375b894a467
LinuxLinux	Affected ≥ 4ddbcb886268af8d12a23e6640b39d1d9c652b1b, < 55bbebf2829c3f47c5a48fc261740301d0f25f48	Fixed in 55bbebf2829c3f47c5a48fc261740301d0f25f48
LinuxLinux	Affected ≥ 4ddbcb886268af8d12a23e6640b39d1d9c652b1b, < 23da88d1597ee7fdda373e1530284b763710911f	Fixed in 23da88d1597ee7fdda373e1530284b763710911f
LinuxLinux	Affected ≥ 4ddbcb886268af8d12a23e6640b39d1d9c652b1b, < 5b52417c6196e05618a3b5d9753dbed9adef0166	Fixed in 5b52417c6196e05618a3b5d9753dbed9adef0166
LinuxLinux	Affected =6.5	Fixed in–

AI-suggested

A fix is available and has been applied in Linux kernel version 6.5 and related commits. Users should update to the fixed kernel versions to remediate this issue. No additional mitigation steps are indicated or required beyond applying the official patch.

Description

A vulnerability in the Linux kernel's TCP stack was fixed where the function cond_resched() was called in an invalid context under BPF (Berkeley Packet Filter) execution. This caused a kernel BUG due to a sleeping function being invoked while holding RCU read locks, which is not allowed. The issue occurs during socket destruction when a listening socket with children in its accept queue is aborted, triggering the problematic cond_resched() call. The fix involves skipping cond_resched() in this specific BPF context to avoid the invalid sleep.

Impact

The vulnerability causes a kernel BUG triggered by an invalid sleeping function call under RCU read lock during BPF socket destruction. This can lead to kernel crashes or instability when running BPF programs that iterate over TCP sockets, potentially affecting system reliability and availability. There is no indication of remote code execution or privilege escalation from the provided data.

Summary

CVE-2026-98646 addresses a Linux kernel vulnerability where cond_resched() is called within inet_csk_listen_stop() during BPF socket destruction under an RCU read lock context. The bpf_sock_destroy() function runs under rcu_read_lock(), and if the socket is a listener with children in its accept queue, tcp_abort() calls inet_csk_listen_stop(), which calls cond_resched(). This leads to a kernel BUG due to sleeping in an invalid context (RCU read lock held). The patch adds a guard to skip cond_resched() in this BPF context, similar to existing guards in tcp_abort() and udp_abort(). The flaw was fixed in Linux kernel version 6.5 and related commits.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 10:04 UTC

Technical details

References

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