CVE-2026-43198 — tcp: fix potential race in tcp_v6_syn_recv_sock()
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.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.3% (30-day exploitation probability)+3
- Technical severity (critical)+10
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes matching the vulnerability class (logic error), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Linux | Linux |
≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < aef4a9ae95d1bc4f7897065011e6261026719aebversion 2.6.12≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 858d2a4f67ff69e645a43487ef7ea7f28f06deae≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 7178e2a8027423b2af17ab95df73a749a5b72e5b≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < fe89b2f05b854847784f91127319172945c1fadd≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 9ed654e340f4c73bc6f0af2fbc90ac293e645ce0≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < cd644e6dc72eec8d9d988717ea1c54f8668ded69≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < a7e761ba55efaa9c49e0afdd304bb78167af3429 and 1 more≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < dad1fe7db6c6519138430ac8f5e589c18f83bfc9 |
Vulnerable | CVE Program (cve.org) e CISA ADP |
| Linux | Linux Kernel | ≥ 2.6.12.1 and < 6.18.16version 7.0-rc1version 2.6.12-rc5version 2.6.12-rc4version 2.6.12-rc3version 2.6.12-rc2version 2.6.12≥ 6.19 and < 6.19.6 | Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 9.8 | CVSS 3.1 | Critical | 3.9 | 5.9 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database |
| 9.8 | CVSS 3.1 | Critical | — | — | Linux via CVE Program (cve.org) e CISA ADP |
| 7.0 | CVSS 3.1 | High | 1.0 | 5.9 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c via NIST National Vulnerability Database |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.30%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · linux/linux
- Record published
- Fix documented
- CVSS changed · 9.8
- Source status changed · → Modified
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
25 on the record
- git.kernel.org/stable/c/fe89b2f05b854847784f91127319172945c1fadd
- git.kernel.org/stable/c/7178e2a8027423b2af17ab95df73a749a5b72e5b
- git.kernel.org/stable/c/858d2a4f67ff69e645a43487ef7ea7f28f06deae
- access.redhat.com/errata/RHSA-2026:36348
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43198.json
- access.redhat.com/errata/RHSA-2026:33215
- git.kernel.org/stable/c/9ed654e340f4c73bc6f0af2fbc90ac293e645ce0
- access.redhat.com/errata/RHSA-2026:34443
- access.redhat.com/errata/RHSA-2026:30129
- access.redhat.com/errata/RHSA-2026:36073
- git.kernel.org/stable/c/cd644e6dc72eec8d9d988717ea1c54f8668ded69
- access.redhat.com/errata/RHSA-2026:41236
- access.redhat.com/errata/RHSA-2026:36216
- git.kernel.org/stable/c/dad1fe7db6c6519138430ac8f5e589c18f83bfc9
- access.redhat.com/security/cve/CVE-2026-43198
- access.redhat.com/errata/RHSA-2026:34094
- access.redhat.com/errata/RHSA-2026:33285
- bugzilla.redhat.com/show_bug.cgi
- access.redhat.com/errata/RHSA-2026:35904
- access.redhat.com/errata/RHSA-2026:35896
- access.redhat.com/errata/RHSA-2026:35863
- git.kernel.org/stable/c/aef4a9ae95d1bc4f7897065011e6261026719aeb
- git.kernel.org/stable/c/a7e761ba55efaa9c49e0afdd304bb78167af3429
- access.redhat.com/errata/RHSA-2026:36349
- access.redhat.com/errata/RHSA-2026:35894
Elsewhere on this site
Related CVEs (same products)
- Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 14h
- Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 14h
- Unknown CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
- Unknown CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
- Unknown CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
- Unknown CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 1d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-43198 is "tcp: fix potential race in tcp_v6_syn_recv_sock()", rated Critical. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 0.30% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
Comments
Moderated technical discussion. Read the community guidelines.
No comments yet.
Sign in or create an account to comment and suggest corrections.