CVE-2026-98432
In the Linux kernel, the following vulnerability has been resolved: ipv4: free inet_opt and ireq_opt after an RCU grace period tcp_v4_syn_recv_sock() transfers ownership of ireq->ireq_opt to the child socket (newinet->inet_opt) without copying it. Another cpu can concurrently process a retransmitted SYN for the same request socket, and send a SYNACK from tcp_check_req(). tcp_v4_send_synack() and inet_csk_route_req() read ireq->ireq_opt under rcu_read_lock() only, and ip_build_and_send_pkt() and ip_options_build() then read opt->optlen twice. Note that the SYNACK timer itself is not an issue: it holds a reference on its request socket, and inet_csk_reqsk_queue_drop() calls timer_delete_sync() before the child can be freed. Since commit 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table"), request sockets are processed without holding the listener lock, so nothing prevents the child socket from being freed while the SYNACK is still being built. TCP child sockets do not have SOCK_RCU_FREE, and inet_sock_destruct() frees inet_opt with a plain kfree(), leading to a use-after-free in ip_options_build(). A similar issue exists with request socket migration (net.ipv4.tcp_migrate_req=1, or a BPF_SK_REUSEPORT_SELECT_OR_MIGRATE program). reqsk_timer_handler() clones the request socket with inet_reqsk_clone(), so that the old request socket and its clone share the same ireq_opt, then reqsk_migrate_reset() clears the pointer in the old one. Another cpu holding a reference on the old request socket can still be using these options (sending a SYNACK, or creating a child in tcp_v4_syn_recv_sock()) when the clone is freed, and tcp_v4_reqsk_destructor() also uses a plain kfree(). Readers already use RCU, and other paths replacing inet_opt (do_ip_setsockopt(), cipso_v4_sock_setattr()...) already use kfree_rcu(). Use kfree_rcu() in inet_sock_destruct() and tcp_v4_reqsk_destructor() as well. IPv6 is not affected by the first issue, because tcp_v6_syn_recv_sock() duplicates the options. tcp_v6_reqsk_destructor() has the same migration issue with ipv6_opt, which is only set by CALIPSO. This will be addressed in a separate patch.
- CVSS
- 9.8Criticalscored by the publisher (CNA)
- Exploited in the wild
- Not knownUnvetted proof-of-concept code on GitHub; not in CISA KEV
- EPSS
- 0.76%chance of exploitation in the next 30 daystop 45% of scored CVEsFIRST score of 11 Nov 2026
- Fix
- Fixed in < 4.4, >= 5.10.272 and <= 5.10.*, >= 5.15.223 and <= 5.15.*per the vendor; 6 more listed below
- Published
- 15 Oct 2026analysed here 12 Nov 2026
Do first. Upgrade to a fixed release: < 4.4, >= 5.10.272 and <= 5.10.*, >= 5.15.223 and <= 5.15.*, >= 6.1.190 and <= 6.1.* (and 5 more below).
Summary
Triage
- Exploitable
- At runtime
- Attack vector
- network
- Can a WAF block it?
- Partly. See why
The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.
Affected products
| Product | Affected versions | Vendor says fixed in |
|---|---|---|
| Linux | >= 079096f103faca2dd87342cca6f23d4b34da8871 and < b3b027ef0cd322bfa839b9aaf5b27551eea54cf6>= 079096f103faca2dd87342cca6f23d4b34da8871 and < 95a8c8fa9f27dce64c40c41c062de7728bf34ab5>= 079096f103faca2dd87342cca6f23d4b34da8871 and < 89b5b1eb7d633c33832b7ff2c02e19a144705036>= 079096f103faca2dd87342cca6f23d4b34da8871 and < 742f73df544e03744f2981c467d6542fe8172a2a>= 079096f103faca2dd87342cca6f23d4b34da8871 and < 11a03ce3c4a62d84c10ccdfe47f8075006498568>= 079096f103faca2dd87342cca6f23d4b34da8871 and < a47406c769f72c070386985488f1c4d057df86b2>= 079096f103faca2dd87342cca6f23d4b34da8871 and < 26d4c36d318cffbbd160884a0e4cec0da4da4936>= 079096f103faca2dd87342cca6f23d4b34da8871 and < e3f33b0a1d89d738e2b913dab519226eaf76e15b4.4Vendor says fixed in: < 4.4, >= 5.10.272 and <= 5.10.*, >= 5.15.223 and <= 5.15.*, >= 6.1.190 and <= 6.1.*, >= 6.6.159 and <= 6.6.*, >= 6.12.113 and <= 6.12.*, >= 6.18.56 and <= 6.18.*, >= 7.2.10 and <= 7.2.*, >= 7.3 and <= * |
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
Fix and mitigation
WAF and other mitigations
Can a WAF block it? Partly. The bug can be reached over the network, so generic WAF rules may stop some attacks. Its weakness type is unknown, so we cannot be more precise.
Also consider: patch
Based on the weakness type only; no CVE-specific evidence yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Remediation steps (AI-written)
Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.
Exploitation evidence
- CISA KEV catalog
- Not listed as of our last sync.
- Public exploit code
- Unvetted proof-of-concept code on GitHub: 50 GitHub proofs of concept
GitHub proofs of concept
- H1z3-br0/CVE-2026-9843211 stars
- tc4dy/CVE-2026-98432-PoC-Exploit10 stars
- xen0bit/netprobe-cve-2026-9843210 stars
- Alucard0x1/cve-2026-9843210 stars
and 46 more repositories
Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.
Timeline
- 26 Sept 2026First proof-of-concept repository on GitHub (unvetted)
- 15 Oct 2026Published20 days later
- 31 Oct 2026CVE record last updated16 days later
- 12 Nov 2026Analysed by vulneraibility.com12 days later
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
| Metric | Value | What it means |
|---|---|---|
| Attack vector | NetworkReachable over the internet or any routable network. | Reachable over the internet or any routable network. |
| Attack complexity | LowRepeatable attack, no special conditions. | Repeatable attack, no special conditions. |
| Privileges required | NoneThe attacker needs no prior access. | The attacker needs no prior access. |
| User interaction | NoneNo victim action needed. | No victim action needed. |
| Scope | UnchangedImpact stays within the vulnerable component. | Impact stays within the vulnerable component. |
| Confidentiality | HighTotal data disclosure possible. | Total data disclosure possible. |
| Integrity | HighComplete modification possible. | Complete modification possible. |
| Availability | HighFull outage possible. | Full outage possible. |
Common questions
Is CVE-2026-98432 being exploited?
Not confirmed. CVE-2026-98432 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.76% probability of exploitation in the next 30 days.
How severe is CVE-2026-98432?
CVE-2026-98432 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-98432?
Not known from our data. No patch reference has been recorded for CVE-2026-98432, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
References
11 references in the CVE record, grouped by the tags the record gives them.
Other links (11)
- git.kernel.org /stable/c/b3b027ef0cd322bfa839b9aaf5b27551eea54cf6
- git.kernel.org /stable/c/95a8c8fa9f27dce64c40c41c062de7728bf34ab5
- git.kernel.org /stable/c/89b5b1eb7d633c33832b7ff2c02e19a144705036
- git.kernel.org /stable/c/742f73df544e03744f2981c467d6542fe8172a2a
- git.kernel.org /stable/c/11a03ce3c4a62d84c10ccdfe47f8075006498568
- git.kernel.org /stable/c/a47406c769f72c070386985488f1c4d057df86b2
Show 5 more
- git.kernel.org /stable/c/26d4c36d318cffbbd160884a0e4cec0da4da4936
- git.kernel.org /stable/c/e3f33b0a1d89d738e2b913dab519226eaf76e15b
- openwall.com /lists/oss-security/2026/10/30/1
- openwall.com /lists/oss-security/2026/10/30/6
- openwall.com /lists/oss-security/2026/10/31/5
Where the data on this page comes from
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- FIRST EPSS: exploit probability and percentile
- PoC-in-GitHub: GitHub repositories that claim a proof of concept
Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
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