Kernel-memory disclosure via congestion-control name race
Published Oct 28, 2026 · Updated Oct 28, 2026
Use-after-free in Linux TCP_CONGESTION handling allows local users to read freed kernel memory through racing socket-option calls. The do_tcp_getsockopt() function copies icsk_ca_ops->name without RCU protection while setsockopt(TCP_CONGESTION) concurrently replaces and frees the BPF congestion-control object. Exposure requires dynamically allocated BPF congestion-control state and overlapping socket-option operations; the documented failure is a stale-memory read, not demonstrated code execution.
Summary
What happened
Use-after-free in Linux TCP_CONGESTION handling allows local users to read freed kernel memory through racing socket-option calls. The do_tcp_getsockopt() function copies icsk_ca_ops->name without RCU protection while setsockopt(TCP_CONGESTION) concurrently replaces and frees the BPF congestion-control object. Exposure requires dynamically allocated BPF congestion-control state and overlapping socket-option operations; the documented failure is a stale-memory read, not demonstrated code execution.
The record
- CVE
- CVE-2026-99139
- Published
- Oct 28, 2026
- Updated
- Oct 28, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Oct 28, 2026CVE publishedPublication date reported by the CVE source.
- Oct 28, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 <5271b79b7ad68dcb222e893773f92bdabf7750f3
- Affected versionversion=0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 <a8e45471afa230c1431c26c8e99ec24377e3b514
- Affected versionversion=0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 <c1804ef016392dd91267d2207ee43b1de34302ca
- Affected versionversion=5.6
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
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Technologies
Your stack
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Your stack
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