CVE-2026-63912
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk50th percentile - higher than 50% of all known CVEs
Summary
In the Linux kernel's ESP (Encapsulating Security Payload) IPsec subsystem, a vulnerability was found in the fast path packet processing due to incorrect fragment length checking. When the combined aligned length exceeds a page size, the destination buffer may be allocated as a single page while the scatter-gather list expects a larger area, leading to a potential buffer overflow.
Risk Assessment
The organization faces risk of system crashes or potential arbitrary code execution due to buffer overflow during IPsec traffic processing. An attacker could exploit this by sending crafted ESP packets, compromising system integrity and availability.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit restoring the combined-length page gate for both IPv4 and IPv6). Before updating, restrict trusted IPsec connections and monitor systems for unusual events.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: xfrm: esp: restore combined single-frag length gate The ESP out-of-place fast path appends the trailer in esp_output_head() before esp_output_tail() allocates the destination page frag. The head-side gate currently checks skb->data_len and tailen separately, but the tail code allocates a single destination frag from the combined post-trailer skb->data_len. Reject the page-frag fast path when the combined aligned length exceeds a page. Otherwise skb_page_frag_refill() may fall back to a single page while the destination sg still spans the combined skb->data_len. Restore this combined-length page gate for both IPv4 and IPv6.