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High, CVSS 8.7amended

kin-openapi has uncontrolled resource consumption in openapi3filter deepObject query parameter decoding

CVE-2026-77354GHSA-xhj3-7xw9-vr34

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/getkin/kin-openapi 0.142.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-77354: 0.52% estimated exploitation activity in the next 30 days; percentile 44.47 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary An uncontrolled resource consumption vulnerability in openapi3filter lets any unauthenticated client force multi-gigabyte heap allocation with a single, tiny HTTP request. When a spec declares a deepObject-style query parameter whose schema contains an array (a normal, documented pattern), the decoder reconstructs the array by reading the largest attacker-supplied index and allocating one slot for every position from 0 up to that index — before schema validation (including maxItems) ever runs. A request as small as 24 bytes (?param[items][50000000]=x) drives heap allocation to ~6.1 GiB, reliably triggering an OOM kill / restart loop on memory-constrained services. Details The OpenAPI style: deepObject serialization lets clients express arrays in the query string using bracket notation, e.g. param[items][0]=a&param[items][1]=b. The decoder first collects these into an intermediate map[string]any keyed by the string of the index, then converts that sparse map into a real []any…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-xhj3-7xw9-vr34

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record GO-2026-6275

  4. Revision 1 · created ·

    Published from osv record GHSA-xhj3-7xw9-vr34

Agent brief

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# Patch Next advisory brief: CVE-2026-77354

Advisory: kin-openapi has uncontrolled resource consumption in openapi3filter deepObject query parameter decoding
IDs: CVE-2026-77354, GHSA-xhj3-7xw9-vr34
Record: https://patchnext.com/advisories/cve-2026-77354 (revision 4, source checked 26 Oct 2026, 15:28 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
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 0.142.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/getkin/kin-openapi: affected >= 0.124.0, < 0.142.0; fixed in 0.142.0

## 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-xhj3-7xw9-vr34 (OSV record GHSA-xhj3-7xw9-vr34 lists affected ranges: Go github.com/getkin/kin-openapi >=0.124.0 <0.142.0 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6275 (OSV record GO-2026-6275 lists affected ranges: Go github.com/getkin/kin-openapi >=0.124.0 <0.142.0 (fixed))
- Verified: https://github.com/advisories/GHSA-xhj3-7xw9-vr34 (GitHub-reviewed advisory GHSA-xhj3-7xw9-vr34 lists affected ranges: Go github.com/getkin/kin-openapi >=0.124.0 <0.142.0)

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