CVE-2026-43198: Linux kernel · tcp: fix potential race in tcp_v6_syn_recv_sock()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 9.8 Critical · fixed in fe89b2f05b854847784f91127319172945c1fadd : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 14:18 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers can reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in fe89b2f05b854847784f91127319172945c1fadd, dad1fe7db6c6519138430ac8f5e589c18f83bfc9, cd644e6dc72eec8d9d988717ea1c54f8668ded69 +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 6 May 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.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
In the Linux kernel, the following vulnerability has been resolved: tcp: fix potential race in tcp_v6_syn_recv_sock() Code in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock() is done too late. After tcp_v4_syn_recv_sock(), the child socket is already visible from TCP ehash table and other cpus might use it. Since newinet->pinet6 is still pointing to the listener ipv6_pinfo bad things can happen as syzbot found. Move the problematic code in tcp_v6_mapped_child_init() and call this new helper from tcp_v4_syn_recv_sock() before the ehash insertion. This allows the removal of one tcp_sync_mss(), since tcp_v4_syn_recv_sock() will call it with the correct context.
References
- git.kernel.org/stable/c/aef4a9ae95d1bc4f7897065011e6261026719aeb (opens in a new tab)
- git.kernel.org/stable/c/dad1fe7db6c6519138430ac8f5e589c18f83bfc9 (opens in a new tab)
- git.kernel.org/stable/c/a7e761ba55efaa9c49e0afdd304bb78167af3429 (opens in a new tab)
- git.kernel.org/stable/c/cd644e6dc72eec8d9d988717ea1c54f8668ded69 (opens in a new tab)
- git.kernel.org/stable/c/9ed654e340f4c73bc6f0af2fbc90ac293e645ce0 (opens in a new tab)
- git.kernel.org/stable/c/fe89b2f05b854847784f91127319172945c1fadd (opens in a new tab)
- git.kernel.org/stable/c/7178e2a8027423b2af17ab95df73a749a5b72e5b (opens in a new tab)
- git.kernel.org/stable/c/858d2a4f67ff69e645a43487ef7ea7f28f06deae (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-43198 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2467228 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43198.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36216 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:41236 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33215 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:30129 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36073 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:34443 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:34094 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33285 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36349 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:35896 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:35894 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:35863 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36348 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:35904 (opens in a new tab)