CVE-2026-98968

HIGH CVSS 8.1 PoC Available
Published: 2026-10-23
Modified: 2026-10-24
Enriched via mock
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AI Threat Summary

CVE-2026-98968 is a high-severity vulnerability with a CVSS score of 8.1 affecting the target software. Threat hunters should monitor for exploit attempts and apply vendor patches immediately.

Description

In the Linux kernel, the following vulnerability has been resolved: amt: send the relay's General Query directly from the receive path An skb queued in a qdisc can outlive the tunnel it references through a raw pointer in skb->cb. For example, with igmp_qrv set to 1 on the relay a tunnel lives for 135s, so a netem delay of 180s on the amt device outlives it; when the tunnel expires and is freed, the subsequent dequeue triggers a use-after-free in amt_dev_xmit(). BUG: KASAN: slab-use-after-free in amt_dev_xmit+0x2763/0x2e20 Call Trace: amt_dev_xmit+0x2763/0x2e20 [drivers/net/amt.c:1262] dev_hard_start_xmit+0x22f/0x620 sch_direct_xmit+0x12e/0xac0 netem_dequeue+0x333/0xc50 net_tx_action+0x35c/0xa60 amt_send_igmp_gq() and amt_send_mld_gq() are only called from amt_request_handler(), inside the rcu_read_lock_bh() section of amt_rcv(). amt_request_handler() already has the tunnel the query is for: it found or created it inside that section. Queuing the query with dev_queue_xmit() only leads back into amt_dev_xmit(), which strips the Ethernet header and calls amt_send_membership_query() for that tunnel. Make that call directly from the two senders instead, the same way amt_send_advertisement() transmits from the receive path. The query never waits in a qdisc, the tunnel is only dereferenced inside the RCU section that found or created it, and nothing is stored in skb->cb, so no lookup or refcount is needed. Remove the query branch of amt_dev_xmit(), amt_skb_cb() and struct amt_skb_cb, which have no users left. Behaviour changes: - The relay's own General Queries no longer pass through the amt device's egress path: its qdisc, tc egress (clsact/tcx), the netfilter egress hook and packet taps. They are still visible as UDP on the underlay. - A query that is sent successfully is no longer counted as tx_dropped. The old query branch left through the unlock label, which counted every sent query as dropped. - A query that reaches amt_dev_xmit() on a relay from elsewhere, such as a userspace querier, is now dropped at the IGMP/MLD type switch. Before, it trusted whatever skb->cb held, and a NULL tunnel hit the WARN_ON(1).

Attack Chain
1
Reconnaissance

Attacker scans for vulnerable versions using version banners or PoC scanners

2
Initial Access

Attacker triggers CVE-2026-98968 vulnerability with a crafted request or payload

3
Execution

Vulnerability exploited to perform unauthorized actions on the target system

4
Impact

Depending on vulnerability type, attacker achieves data access, service disruption, or code execution

MITRE ATT&CK Techniques
T1190 Exploit Public-Facing Application
Initial Access

Public-facing application vulnerability exploited for initial access

T1203 Exploitation for Client Execution
Execution

Vulnerability exploited to execute attacker-controlled code

Indicators of Compromise
Type Value Description
user_agent Mozilla/5.0 (compatible; exploit/1.0) Generic exploit scanner user agent pattern
url /api/vuln-endpoint?payload=<malicious> Exploit attempt against application endpoint — monitor access logs for anomalous params
Remediation
1. Apply vendor-supplied security patches immediately. 2. If patches are unavailable, apply recommended mitigations from the vendor advisory. 3. Enable WAF rules or IDS signatures to detect exploitation attempts. 4. Monitor logs for indicators of compromise listed above. 5. Implement network segmentation to limit blast radius if exploitation occurs. 6. Subscribe to vendor security advisories for this product.
Quick Facts
CVE ID CVE-2026-98968
CVSS Score 8.1
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Published 2026-10-23
Exploited No
CISA KEV No
PoC Available
References
External Resources
NVD Entry BleepingComputer The Hacker News