avro vulnerable to denial of service via attacker-controlled parameter

Exploitation

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

CVSS

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

EPSS

• CVE-2023-37475: 0.95% estimated exploitation activity in the next 30 days; percentile 61.38 (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 A well-crafted string passed to avro's github.com/hamba/avro/v2.Unmarshal() can throw a fatal error: runtime: out of memory which is unrecoverable and can cause denial of service of the consumer of avro. Details The root cause of the issue is that avro uses part of the input to Unmarshal() to determine the size when creating a new slice. In the reproducer below, the first few bytes determine the size of the slice. The root cause is on line 239 here: https://github.com/hamba/avro/blob/3abfe1e6382c5dccf2e1a00260c51a64bc1f1ca1/reader.go#L216-L242 PoC The issue was found during a security audit of Dapr, and I attach a reproducer that shows how the issue affects Dapr. Dapr uses an older version of the avro library, but it is also affected if bumping avro to latest. To reproduce: now add this test to the pulsartest.go: run the test with go test -run=TestParsePublishMetadata2. You should see this stacktrace: Impact Any use case of the avro Unmarshalling routine that accepts…

Published by the source

17 Jul 2023, 10:55 UTC

Last modified by the source

6 Nov 2023, 05:03 UTC

Source last checked

26 Oct 2026, 14:59 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-9x44-9pgq-cf45

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# Patch Next advisory brief: CVE-2023-37475

Advisory: avro vulnerable to denial of service via attacker-controlled parameter
IDs: CVE-2023-37475, GHSA-9x44-9pgq-cf45
Record: https://patchnext.com/advisories/cve-2023-37475 (revision 1, source checked 26 Oct 2026, 14:59 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/hamba/avro/v2 2.13.0; github.com/hamba/avro 2.13.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/hamba/avro/v2: affected < 2.13.0; fixed in 2.13.0
- Go github.com/hamba/avro: affected < 2.13.0; fixed in 2.13.0

## Suggested inspection (read-only)
- Go github.com/hamba/avro/v2: check the installed version with your package manager.
- Go github.com/hamba/avro: 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/hamba/avro/v2, github.com/hamba/avro.
- 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://github.com/advisories/GHSA-9x44-9pgq-cf45 (GitHub-reviewed advisory GHSA-9x44-9pgq-cf45 lists affected ranges: Go github.com/hamba/avro >=0 =0 <2.13.0)

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