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CVE-2026-69208· NVD / CVE Program· CNA GitHub_M

Http4s: DigestAuth nonce map grows unbounded

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, the DigestAuth server middleware removes fresh nonces and stops eviction at the first stale nonce because its stale-nonce comparison is inverted. On an application that protects at least one route with DigestAuth, an unauthenticated attacker can repeatedly trigger authentication challenges, causing the persistent nonce map to grow until the JVM exhausts heap memory. This issue is fixed in versions 0.23.35 and 1.0.0-M47.

HighCVSS 7.5 · v3.1—No exploit Fix available

Noroxi analysis

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Published
Sep 15, 2026
Updated
Sep 17, 2026
EPSS
0.8% · 54th percentile
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Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.8%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
7.5
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • http4s http4s

    • < 0.23.35, >= 1.0.0-M1, < 1.0.0-M47affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Mavenorg.http4s:http4s-ember-server_2.12before 0.23.350.23.35
Mavenorg.http4s:http4s-ember-server_2.13from 1.0.0-M1 · before 1.0.0-M471.0.0-M47
Mavenorg.http4s:http4s-ember-server_2.13before 0.23.350.23.35
Mavenorg.http4s:http4s-ember-server_3from 1.0.0-M1 · before 1.0.0-M471.0.0-M47
Mavenorg.http4s:http4s-ember-server_3before 0.23.350.23.35

Same product

http4s: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-69204Http4s: Ember accepts Transfer-Encoding combined with Content-Length (CL.TE request smuggling)
    36Monitor
  • CVE-2026-69217Http4s: Ember Server accepts duplicate Content-Length headers
    34Monitor
  • CVE-2026-69205Http4s: Ember Transfer-Encoding value parsing (TE.CL / TE.0 request smuggling)
    34Monitor
  • CVE-2026-54556Http4s: HTTP/2 Denial of Service with Ember Backend
    32Monitor
  • CVE-2026-88975Http4s: Ember HTTP/2 buffers a frame's declared payload before checking SETTINGS_MAX_FRAME_SIZE
    30Monitor
  • CVE-2026-69218Http4s Ember HTTP/2: unbounded continuation frame accumulation
    30Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Maven:org.http4s:http4s-ember-server_2.120.23.35Package registry (OSV)
Maven:org.http4s:http4s-ember-server_2.130.23.35Package registry (OSV)
Maven:org.http4s:http4s-ember-server_2.131.0.0-M47Package registry (OSV)
Maven:org.http4s:http4s-ember-server_30.23.35Package registry (OSV)
Maven:org.http4s:http4s-ember-server_31.0.0-M47Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-692020 days apartHttp4s Ember HTTP/2: unbounded inbound body buffering
    30Monitor
  • CVE-2026-692030 days apartHttp4s Ember HTTP/2: does not enforce SETTINGS_MAX_CONCURRENT_STREAMS
    30Monitor
  • CVE-2026-692090 days apartHttp4s: WebSocket decoder accepts unbounded message sizes
    30Monitor
  • CVE-2026-692130 days apartHttp4s Ember HTTP/2: unbounded outbound frame queue
    30Monitor
  • CVE-2026-889750 days apartHttp4s: Ember HTTP/2 buffers a frame's declared payload before checking SETTINGS_MAX_FRAME_SIZE
    30Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-400 · Uncontrolled Resource Consumption

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-secondary

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

The bug in code

The whole CWE-400 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
function expand(node) {  return node.children.map(expand);}

Fixed

ts
const MAX_DEPTH = 32;function expand(node, depth = 0) {  if (depth > MAX_DEPTH) throw new Error("too deep");  return node.children.map((c) => expand(c, depth + 1));}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records