Linux · Kernel · Linux Kernel Heap Out-of-Bounds Write Vulnerability
Verdict
Patch soon · actively exploited, not reachable unauthenticated from the internet, and in the top 1% of CVEs by near-term exploitation probability
Added to CISA KEV 2025-10-06 · exploited in the wild for 356 days
CVSS 8.3 HIGH. The score is a summary; these three components are the part that decides whether something scanning the internet can use it.
| Attack vector | adjacent networkonly reachable from an adjacent network, such as a shared segment or a VPN concentrator |
|---|---|
| Privileges required | noneneeds no credentials at all |
| User interaction | nonecan be triggered with nobody interacting with the page or request |
| Base vector | CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H |
| Weakness | CWE-787 |
This describes the vulnerability. It says nothing about whether your systems run it.
EPSS puts the probability of exploitation in the next 30 days at 0.7868, which places it in the top 1% of all tracked CVEs. The percentile is the more useful half: 0.18 in absolute terms sounds low until you know most of the internet-facing software in the world scores under that.
| EPSS probability | 0.7868 |
|---|---|
| Percentile | 0.996 — top 1% |
| Added to KEV | 2025-10-06 |
|---|---|
| Days exploited | 356 |
| Federal remediation due | not set |
| Ransomware use | no known ransomware campaign use |
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
A heap out-of-bounds write affecting Linux since v2.6.19-rc1 was discovered in net/netfilter/x_tables.c. This allows an attacker to gain privileges or cause a DoS (via heap memory corruption) through user name space