CVE-2021-29510

Use of "infinity" as an input to datetime and date fields causes infinite loop in pydantic

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).
Patches

Pydantic is be patched with fixes available in the following versions:

v1.8.2
v1.7.4
v1.6.2

All these versions are available on pypi, and will be available on conda-forge soon.

See the changelog for details.
Workarounds

If you absolutely can't upgrade, you can work around this risk using a validator to catch these values, brief demo:

from datetime import date
from pydantic import BaseModel, validator

class DemoModel(BaseModel):
date_of_birth: date

@validator('date_of_birth', pre=True)
def skip_infinite_values(cls, v):
    try:
        seconds = float(v)
    except (ValueError, TypeError):
        return v
    else:
        if seconds == float('inf'):
            return date.max
        elif seconds == float('-inf'):
            return date.min
        else:
            return seconds

Note: 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 requesting a back-port, and we will endeavour to release a patch for earlier versions of pydantic.
References

This was fixed in commit 7e83fdd.

CVE-2021-29510 has a CVSS score of 3.3 (Medium). The vector is requires local access, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.6.2, 1.8.2, 1.7.4); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

1. What is CVE-2021-29510? CVE-2021-29510 is a medium-severity security vulnerability in pydantic (pip), affecting versions < 1.6.2. It is fixed in 1.6.2, 1.8.2, 1.7.4.
2. How severe is CVE-2021-29510? CVE-2021-29510 has a CVSS score of 3.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of pydantic are affected by CVE-2021-29510? pydantic (pip) versions < 1.6.2 is affected.
4. Is there a fix for CVE-2021-29510? Yes. CVE-2021-29510 is fixed in 1.6.2, 1.8.2, 1.7.4. Upgrade to this version or later.
5. Is CVE-2021-29510 exploitable, and should I be worried? Whether CVE-2021-29510 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-29510 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-29510?
   • Upgrade pydantic to 1.6.2 or later
   • Upgrade pydantic to 1.8.2 or later
   • Upgrade pydantic to 1.7.4 or later

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