---
title: "pyasn1 Breaking Changes on PyPI | Since.dev"
description: "What each pyasn1 release removed, renamed or changed: 4 breaking changes in 4 versions on PyPI, each with its source."
canonical_url: https://since.dev/packages/pypi/pyasn1
last_updated: 2026-10-27
---

# pyasn1 breaking changes

Every breaking API change we have recorded in pyasn1 on PyPI: 4 breaking changes in 4 versions. Below are its newest 4 versions, removals and renames first, each with its source.

Newest change October 27, 2026

## 0.6.5

1 breaking change, first published October 27, 2026.

- **Behavior changed**  

Decoding nested constructed OCTET STRING fragments now includes their octets in the result, so code that relied on the earlier output may see different values. [github.com](https://github.com/pyasn1/pyasn1/releases/tag/v0.6.5)

## 0.6.4

1 breaking change, first published July 9, 2026.

- **Behavior changed**  

BER long-form tag IDs are limited to 20 octets (140 bits); substrate that previously decoded with longer tag IDs will now fail to decode. [github.com](https://github.com/pyasn1/pyasn1/releases/tag/v0.6.4)

## 0.6.3

1 breaking change, first published March 17, 2026.

- **Behavior changed**  

The ASN.1 decoder now rejects deeply nested structures beyond a new depth limit to prevent stack overflow. Code that decodes unusually deep structures may now get an error and may need to handle it. [github.com](https://github.com/pyasn1/pyasn1/releases/tag/v0.6.3)

## 0.6.2

1 breaking change, first published January 16, 2026.

- **Behavior changed**  

The decoder now rejects OID and RELATIVE-OID encodings with too many continuation octets, as a security fix for CVE-2026-23490. Code that decodes very long OIDs may now get an error where it previously succeeded. [github.com](https://github.com/pyasn1/pyasn1/releases/tag/v0.6.2)

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