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CVE-2023-52881 is an improper TCP ACK-validation flaw in the Linux kernel TCP implementation. For newly established, potentially spoofed flows, Linux could accept ACK values within the RFC 5961-derived acceptable window even when those ACKs acknowledged bytes that the server had never transmitted. An attacker can use these "ghost ACKs" to probe and brute-force the server-selected TCP send window. Associated side channels can disclose the server's TCP initial sequence number (ISN), including a side channel involving TCP SYN cookies. The fix tightens ACK validation so ACKs for unsent bytes are rejected and handled with a challenge ACK rather than accepted.
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What an attacker gets, and what they’ve been doing with it.
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Patch, then assume compromise.
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
24 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Linux kernel TCP issue involving spoofed ghost ACKs and exposure of an initial sequence number.
Linux kernel TCP issue involving spoofed ghost ACKs and initial sequence-number disclosure.
Linux kernel TCP flaw involving spoofed ghost ACKs that can leak the initial sequence number.
A Linux kernel TCP flaw involving spoofed ghost ACKs and possible leakage of an initial sequence number.
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.