Actively exploited in the wild
Linux Kernel Unspecified Vulnerability
Linux - Kernel · Listed in the CISA KEV since 2026-08-27. This indicates confirmed attacks in production environments.
Required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
CVE-2026-53362
HighCVSS 7.8KEVExploitation Probability (EPSS)
Low risk41th percentile - higher than 41% of all known CVEs
Summary
In the Linux kernel's __ip6_append_data() function for IPv6, a bug was found in the buffer size calculation for the paged allocation path. Incorrect accounting of fraggap (extra bytes carried over between packets) causes the linear area of the skb to be undersized, leading to data being copied past its end and overwriting skb_shared_info structures. An unprivileged user can trigger this via a UDPv6 socket with MSG_MORE and MSG_SPLICE_PAGES flags.
Risk Assessment
This vulnerability allows a local, unprivileged user to corrupt kernel memory, potentially leading to system crashes (kernel panic) or privilege escalation.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit correcting fraggap calculation in __ip6_append_data()). As a mitigation before patching, restrict the use of MSG_SPLICE_PAGES for UDPv6 sockets by unprivileged users.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ipv6: account for fraggap on the paged allocation path In __ip6_append_data(), when the paged-allocation branch is taken (MSG_MORE / NETIF_F_SG / large fraglen), alloclen and pagedlen are computed as alloclen = fragheaderlen + transhdrlen; pagedlen = datalen - transhdrlen; datalen already includes fraggap (datalen = length + fraggap). When fraggap is non-zero, this is not the first skb and transhdrlen is zero. The fraggap bytes carried over from the previous skb are copied just past the fragment headers in the new skb's linear area. The linear area is therefore undersized by fraggap bytes while pagedlen is overstated by the same amount, and the copy writes past skb->end into the trailing skb_shared_info. An unprivileged user can trigger this via a UDPv6 socket using MSG_MORE together with MSG_SPLICE_PAGES. The bad accounting was introduced by commit 773ba4fe9104 ("ipv6: avoid partial copy for zc"). Before commit ce650a166335 ("udp6: Fix __ip6_append_data()'s handling of MSG_SPLICE_PAGES"), the negative copy value caused -EINVAL to be returned. That later commit allowed MSG_SPLICE_PAGES to proceed in this case, making the corruption triggerable. The non-paged branch sets alloclen to fraglen, which already accounts for fraggap because datalen does. Bring the paged branch in line by adding fraggap to alloclen and subtracting it from pagedlen. After this adjustment, copy no longer collapses to -fraggap on the paged path, so remove the stale comment describing that old arithmetic. Since a negative copy is no longer expected for a valid MSG_SPLICE_PAGES case, remove the MSG_SPLICE_PAGES exception from the negative copy check.