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CVE-2021-31618 is a NULL pointer dereference in Apache HTTP Server's mod_http2 request-header rejection handling. HTTP/2 request headers are evaluated against configured header-size limits. When an offending header is the first received header or is received in a footer, mod_http2 can construct an incompletely initialized rejection response and subsequently dereference a NULL pointer. The fault reliably terminates the handling child process. The upstream issue affected mod_http2 1.15.17 and Apache HTTP Server 2.4.47; upstream 2.4.47 was never publicly released, while supported downstream distributions may have backported the fix into earlier package versions.
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No public exploit code observed for this vulnerability.
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7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A NULL-pointer dereference vulnerability in Apache HTTP Server (httpd) triggered by a specially crafted HTTP/2 request.
A NULL-pointer dereference flaw in Apache HTTP Server HTTP/2 request processing, triggered by a specially crafted request.
One of several vulnerabilities addressed in Apache HTTP Server (apache2); the advisory states that the vulnerabilities could result in denial of service.
A denial-of-service vulnerability in Apache HTTP Server's HTTP/2 (mod_http2) request-header error handling. Specially crafted HTTP/2 requests can trigger a NULL-pointer dereference and reliably crash an Apache child process.
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.