iskorotkov/avro: Integer Overflow in Decoder

Exploitation

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

CVSS 4.0

8.2 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-46384: 0.55% estimated exploitation activity in the next 30 days; percentile 46.03 (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.

Integer Overflow in Avro Decoder Summary Several Avro decoder paths read attacker-controlled 64-bit values from the wire format and either narrowed them to platform-sized int before bounds-checking, or summed them with overflow-prone signed-int arithmetic. On 32-bit targets (GOARCH=386, arm, mips, wasm, etc.), the truncation paths can silently bypass byte-slice limits, select the wrong union branch, or hit the OCF negative-make panic via wrap. Three sub-issues are not 32-bit-specific: cumulative-size arithmetic overflow in arrayDecoder.Decode / mapDecoder.Decode / mapDecoderUnmarshaler.Decode (wraps at math.MaxInt64 on amd64 / arm64 and bypasses MaxSliceAllocSize / MaxMapAllocSize), math.MinInt negation in block-header handling, and make([]byte, size) with a negative size in OCF block reads — all three panic or bypass caps on any platform, giving an attacker a denial-of-service primitive there. Exploitation requires only an untrusted Avro stream. No primitives reach beyond…

Published by the source

27 Jul 2026, 16:16 UTC

Last modified by the source

5 Aug 2026, 03:41 UTC

Source last checked

26 Oct 2026, 15:23 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mc57-h6j3-3hmv

2. Revision 2 · amended · 25 Oct 2026

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

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GO-2026-5047

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# Patch Next advisory brief: CVE-2026-46384

Advisory: iskorotkov/avro: Integer Overflow in Decoder
IDs: CVE-2026-46384, GHSA-mc57-h6j3-3hmv
Record: https://patchnext.com/advisories/cve-2026-46384 (revision 3, source checked 26 Oct 2026, 15:23 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/iskorotkov/avro/v2 2.33.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/hamba/avro/v2: affected every version
- Go github.com/iskorotkov/avro/v2: affected < 2.33.0; fixed in 2.33.0

## Suggested inspection (read-only)
- Go github.com/hamba/avro/v2: check the installed version with your package manager.
- Go github.com/iskorotkov/avro/v2: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/hamba/avro/v2, github.com/iskorotkov/avro/v2.
- 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/GO-2026-5047 (OSV record GO-2026-5047 lists affected ranges: Go github.com/iskorotkov/avro/v2 >=0 =0)
- Verified: https://github.com/advisories/GHSA-mc57-h6j3-3hmv (GitHub-reviewed advisory GHSA-mc57-h6j3-3hmv lists affected ranges: Go github.com/iskorotkov/avro/v2 >=0 <2.33.0)

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