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Vulnerabilities

Vulnerability · CVE-2026-114129

stream-json: FlexAssembler string/RegExp path filters join the full key stack per container start, giving O(depth^2) CPU denial of service

Published Oct 21, 2026 · catalog updated Oct 21, 2026 · stream-json: FlexAssembler string/RegExp path

Last checked Nov 7, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-114129. EPSS is 0.25%. Act only if a listed version of stream-json: FlexAssembler string/RegExp path is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (stream-json: FlexAssembler string/RegExp path).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.2
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.25%
Remediation
Advisory link
Affected products
npm stream-json · vendor uhop stream-json

stream-json is a micro-library of stream components for processing JSON and JSONC with a minimal memory footprint. From 2.0.0 until 3.7.0, FlexAssembler compiles string and regular-expression path filters into matchers that join the full key stack on every container start. Because the key stack grows with unbounded object or array nesting, a document nested to depth D causes D joins whose cost grows with the current depth, resulting in quadratic CPU consumption on the single-threaded event loop. The join occurs before the rule match decision, so the attacker does not need to know the target schema. Consumers using only function filters or no rules are not affected. A crafted nested document can stall all concurrent work in a process that feeds it to an affected FlexAssembler. This issue is fixed in 3.7.0, which adds a default maximum depth.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • npm stream-jsonversion unspecified
  • vendor uhop stream-jsonversion unspecified

How to fix CVE-2026-114129

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-114129. EPSS is 0.25%. Act only if a listed version of stream-json: FlexAssembler string/RegExp path is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-407. EPSS 0.25%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 22, 2026 · GitLab Advisory Database

    Detected

    FlexAssembler, the custom-container assembler shipped in the stream-json package (src/core/utils/flex-assembler.js, re-exported at stream-json/utils/flex-assembler.js and stream-json/web/utils/flex-assembler.js), compiles a string or RegExp path filter into a matcher that runs keyStack.join(separator) on every container start. Because the key stack grows one entry per open object or array with no

Sources

  • CVE.orgVulnerability recordCVE-2026-114129

    stream-json is a micro-library of stream components for processing JSON and JSONC with a minimal memory footprint. From 2.0.0 until 3.7.0, FlexAssembler compiles string and regular-expression path filters into matchers that join the full key stack on every container start. Becaus

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-114129

    30-day exploitation probability 0.25%

    first.org
  • GitLab Advisory DatabasePackage advisoryCVE-2026-114129

    FlexAssembler, the custom-container assembler shipped in the stream-json package (src/core/utils/flex-assembler.js, re-exported at stream-json/utils/flex-assembler.js and stream-json/web/utils/flex-assembler.js), compiles a string or RegExp path filter into a matcher that runs keyStack.join(separator) on every container start. Because the key stack grows one entry per open object or array with no

    advisories.gitlab.com

References

Freshness

Last verified in this catalog Nov 7, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 7, 2026
  • GitLab Advisory DatabaseOct 23, 2026
  • CVE.orgOct 23, 2026