CVE-2026-99030
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AI Threat Summary
CVE-2026-99030 is a high-severity vulnerability with a CVSS score of 7.5 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: net: skbuff: don't leave stale bytes in skb_copy_and_csum_bits() When skb_copy_and_csum_bits() reaches unreadable frags it returns 0 after copying only the linear part, and the rest of the caller's buffer is left as it was. The callers copy into a buffer that is about to go out on the wire: an ICMP error quoting the offending packet, or a driver's TX bounce buffer in skb_copy_and_csum_dev(). Neither buffer is zeroed beforehand, so whatever was in memory there gets sent. Zero the part of the buffer we didn't fill. The checksum usually won't match the data any more, so the receiver will usually drop the packet, but either way it no longer carries anything it shouldn't. Only zero for a positive @len, a negative one from a broken caller must not turn into a huge memset().
Attack Chain
Attacker scans for vulnerable versions using version banners or PoC scanners
Attacker triggers CVE-2026-99030 vulnerability with a crafted request or payload
Vulnerability exploited to perform unauthorized actions on the target system
Depending on vulnerability type, attacker achieves data access, service disruption, or code execution
MITRE ATT&CK Techniques
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
Quick Facts
| CVE ID | CVE-2026-99030 |
| CVSS Score | 7.5 |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
| Published | 2026-10-23 |
| Exploited | No |
| CISA KEV | No |
| PoC | Available |