What’s Vulnerable › Vulnerabilities

CVE-2026-10725: Protocol::HTTP2 versions before 1.13 for Perl is vulnerable to a HTTP/2 Bomb

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-06 · updated 2026-07-23
• Weakness: CWE-409

Description

Protocol::HTTP2 versions before 1.13 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.

Affected products

• CRUX Protocol::Http2: before 1.13 — fixed in 1.13

How to fix

Upgrade to a fixed version: CRUX Protocol::Http2 1.13. Check the vendor advisory for mitigations.

References

• https://github.com/vlet/p5-Protocol-HTTP2/commit/822bf22224adbd662e8d0b865eeacb2b294d16cd.patch
• https://metacpan.org/release/CRUX/Protocol-HTTP2-1.12/source/lib/Protocol/HTTP2/HeaderCompression.pm#L133
• https://metacpan.org/release/CRUX/Protocol-HTTP2-1.12/source/lib/Protocol/HTTP2/Stream.pm#L414
• https://metacpan.org/release/CRUX/Protocol-HTTP2-1.13/changes
• https://security.metacpan.org/patches/P/Protocol-HTTP2/1.12/CVE-2026-10725-r2.patch
• http://www.openwall.com/lists/oss-security/2026/06/06/7

Get alerted when CVE-2026-10725 or the next vulnerability affects your stack