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CVE-2021-20322 is a side-channel vulnerability in Linux kernel processing of received ICMP error messages, including ICMP Fragmentation Needed and ICMP Redirect packets. An off-path remote attacker can exploit observable signals to rapidly identify open UDP ports and effectively bypass UDP source-port randomization. Applications that depend on source-port unpredictability, including DNS software, are indirectly affected. Fragmented ICMP Echo Replies can also provide a useful signal for DNS poisoning attacks.
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No public exploit code observed for this vulnerability.
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
11 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Linux kernel vulnerability enabling a DNS cache-poisoning attack based on ICMP 'fragment needed' packet replies. Red Hat addresses it through RHSA-2022:4829 in kernel version 4.18.0-305.49.1.el8_4 for the listed Red Hat Enterprise Linux 8.4 products. A reboot is required for the update to take effect.
Linux kernel DNS cache-poisoning issue involving ICMP Fragmentation Needed responses.
Linux kernel DNS cache-poisoning vulnerability based on ICMP Fragmentation Needed replies.
Linux kernel DNS cache-poisoning issue involving ICMP fragmentation-needed replies.
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.