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Fencer Vulns
high 7.5

CVE-2026-16028 json

Protocol::HTTP2 versions before 1.14 for Perl allow memory exhaustion via closed streams that stream_state never removes from the connection stream table

published 2026-09-07 2 mo ago modified 2026-09-08 2 mo ago also EUVD-2026-72527

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

Protocol::HTTP2 versions before 1.14 for Perl allow memory exhaustion via closed streams that stream_state never removes from the connection stream table.

When a stream reaches the CLOSED state, stream_state returns the concurrency slot and clears most of the stream's keys, but the entry itself stays in the connection stream table and nothing in the distribution removes it. Stream identifiers increase monotonically, so a peer can open and close streams on one connection indefinitely, each close leaving a residual entry that is retained for the life of the connection.

SETTINGS_MAX_CONCURRENT_STREAMS does not bound this. That setting caps how many streams are live at once and is enforced, while the growth is made of streams the cap has already released, so it accumulates with concurrency never exceeding one. The client keeps the same table and grows the same way against a hostile server.

Measured against a server built on this module, roughly 920 bytes are retained per closed stream for about 19 bytes on the wire, so 100,000 sequential streams on one connection grow server resident memory by about 88 MiB. The streams are ordinary requests that the application accepts and completes.

Patch / fix

  • crux protocol::http2 1.14
  • libprotocol-http2-perl Debian 14 1.14-1

debian advisories DEBIAN-CVE-2026-16028

  • perl-Protocol-HTTP2 SLES for SAP applications 16.0, SLES 16.0 1.10-160000.4.1
  • perl-Protocol-HTTP2 SLE Module for Package Hub 15 SP7 1.10-150600.3.6.1

suse advisories SUSE-SU-2026:23945-1SUSE-SU-2026:4182-1

  • perl-Protocol-HTTP2 openSUSE Leap 16.0 1.10-160000.4.1
  • perl-Protocol-HTTP2 openSUSE Tumbleweed 1.140.0-1.1

opensuse advisories openSUSE-SU-2026:21972-1openSUSE-SU-2026:11735-1

  • perl-protocol-http2 Alpine 3.24, Alpine 3.23 1.14-r0

alpine advisories ALPINE-CVE-2026-16028

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-16028 updated cvss 7.5

perl-Protocol-HTTP2: Protocol::HTTP2: Denial of Service via memory exhaustion from unremoved closed streams

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.36% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Classification

Weakness
  • CWE-401 Missing Release of Memory after Effective Lifetime

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.