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Fencer Intel
high 7.5

CVE-2026-69218 json

Http4s Ember HTTP/2: unbounded continuation frame accumulation

published last mo. modified last mo. also EUVD-2026-79195 , GHSA-cp4q-fqw9-4hf6

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, When Ember receives an HTTP/2 HEADERS or PUSH_PROMISE frame without END_HEADERS, H2Connection buffers the header block and subsequent CONTINUATION fragments without a size bound. A remote peer can keep an incomplete block open and exhaust heap memory before request decoding, affecting an ember-server or ember-client configured with withHttp2. The remediation tracks accumulated size against SETTINGS_MAX_HEADER_LIST_SIZE derived from EmberServerBuilder.maxHeaderSize or EmberClientBuilder.maxResponseHeaderSize, sends GOAWAY when the limit is exceeded, and applies receiveHeadersTimeout to incomplete blocks. This issue is fixed in versions 0.23.35 and 1.0.0-M47.

Patch / fix

  • maven org.http4s:http4s-ember-core_2.12 0.23.35
  • maven org.http4s:http4s-ember-core_2.13 0.23.35, 1.0.0-M47
  • maven org.http4s:http4s-ember-core_3 0.23.35, 1.0.0-M47
  • typelevel http4s 0.23.35, 1.0.0-M47
  • org.http4s http4s-ember-core_2.12 0.23.35
  • org.http4s http4s-ember-core_2.13 0.23.35, 1.0.0-M47
  • org.http4s http4s-ember-core_3 0.23.35, 1.0.0-M47

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CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

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

Affected packages

ecosystem package affected fixed in
maven org.http4s:http4s-ember-core_2.12
<0.23.35
0.23.35
maven org.http4s:http4s-ember-core_2.13
<0.23.35
>=1.0.0-M1, <1.0.0-M47
0.23.35
1.0.0-M47
maven org.http4s:http4s-ember-core_3
<0.23.35
>=1.0.0-M1, <1.0.0-M47
0.23.35
1.0.0-M47

Affected products

  • http4s http4s

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Intel 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.