Bug 2485660 (CVE-2026-10725)

Summary: CVE-2026-10725 Protocol::HTTP2: Protocol::HTTP2: Denial of Service via HTTP/2 Bomb
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Protocol::HTTP2. This vulnerability, known as an HTTP/2 Bomb, allows a remote attacker to send a small HTTP/2 request that can expand into a large amount of server memory. This is due to the inbound HPACK path having no header-list size limit, leading to an unbounded buffer growth when decoding headers. The primary consequence is a denial of service (DoS) as the server's memory is exhausted.
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Bug Depends On: 2488904    
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Description OSIDB Bzimport 2026-06-06 10:01:15 UTC 
Protocol::HTTP2 versions through 1.12 for Perl is vulnerable to a HTTP/2 Bomb.

Protocol::HTTP2's inbound HPACK path has no header-list size limit, so a small HTTP/2 request can expand into large server memory (the "HTTP/2 bomb").

The headers_decode method materialises a full key+value copy per indexed reference with no running size check, and the stream_header_block_add method appends (since version 1.12) every CONTINUATION frame to the per-stream buffer unbounded.

MAX_HEADER_LIST_SIZE (default 65536) is advertised in SETTINGS but never consulted on decode.  It is absent from the decoder and from the :limits export tag.