kin-openapi deepObject query decoding repeatedly compiles an invariant regular expression

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-100350: 0.45% estimated exploitation activity in the next 30 days; percentile 39.25 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary openapi3filter decodes deepObject-style query parameters by looping over every key in the request's query string. Inside that loop it recompiles a loop-invariant regular expression on every iteration. The pattern depends only on the spec-defined parameter name, not on the loop variable, so it is compiled N times for N query keys instead of once. Because the number of query keys is attacker-controlled and unbounded, a single request with many junk query keys forces a proportional number of regexp.MustCompile calls, consuming CPU. A handful of concurrent requests can saturate all cores — an uncontrolled-resource-consumption denial of service. This is not ReDoS: the pattern is fixed (^<param\) and matches in linear time. The cost is the repeated compilation of an invariant regexp, once per attacker-supplied query key. Details In openapi3filter/reqrespdecoder.go, the deepObject branch of urlValuesDecoder.DecodeObject builds a per-parameter property map by iterating over all…

Published by the source

15 Oct 2026, 20:18 UTC

Last modified by the source

15 Oct 2026, 20:30 UTC

Source last checked

26 Oct 2026, 15:32 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-h4r5-mxv5-8mjc

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-h4r5-mxv5-8mjc

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# Patch Next advisory brief: CVE-2026-100350

Advisory: kin-openapi deepObject query decoding repeatedly compiles an invariant regular expression
IDs: CVE-2026-100350, GHSA-h4r5-mxv5-8mjc
Record: https://patchnext.com/advisories/cve-2026-100350 (revision 2, source checked 26 Oct 2026, 15:32 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/getkin/kin-openapi 0.146.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/getkin/kin-openapi: affected >= 0.145.0, < 0.146.0; fixed in 0.146.0

## Suggested inspection (read-only)
- Go github.com/getkin/kin-openapi: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/getkin/kin-openapi.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-h4r5-mxv5-8mjc (OSV record GHSA-h4r5-mxv5-8mjc lists affected ranges: Go github.com/getkin/kin-openapi >=0.145.0 <0.146.0 (fixed))
- Verified: https://github.com/advisories/GHSA-h4r5-mxv5-8mjc (GitHub-reviewed advisory GHSA-h4r5-mxv5-8mjc lists affected ranges: Go github.com/getkin/kin-openapi >=0.145.0 <0.146.0)

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