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CVE-2025-21765 is an object-lifetime protection flaw in the Linux kernel IPv6 function ip6_default_advmss(). The function reads a network namespace net structure without the necessary read-copy-update (RCU) protection, allowing the structure to disappear during access and creating a potential use-after-free condition. Exploitation by a local, low-privileged attacker can cause denial of service or system instability. The fix adds RCU protection around the affected access.
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11 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Linux kernel IPv6 object-lifetime protection flaw in ip6_default_advmss(), resolved by adding RCU protection to prevent the referenced network structure from disappearing during access. The advisory rates it medium severity, with CVSS v3 5.5 indicating local, low-privilege exploitation and high availability impact.
Linux kernel IPv6 default advertised-MSS RCU protection issue.
A Linux kernel IPv6 race-condition flaw in ip6_default_advmss() caused by missing RCU protection while accessing network structures, potentially affecting availability.
A Linux kernel IPv6 flaw in ip6_default_advmss() caused by missing RCU protection while accessing a network structure, potentially resulting in a local denial of service through availability impact.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.