{"id":"CVE-2021-29510","aliases":["GHSA-5jqp-qgf6-3pvh","PYSEC-2021-47"],"title":"Use of \"infinity\" as an input to datetime and date fields causes infinite loop in pydantic","summary":"Use of \"infinity\" as an input to datetime and date fields causes infinite loop in pydantic","severity":"low","cvss":3.3,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L","vendor":"pydantic","product":"pydantic","ecosystem":"pip","affected":["pydantic < 1.6.2","pydantic >= 1.8, < 1.8.2","pydantic >= 1.7, < 1.7.4"],"patched":["pydantic 1.6.2","pydantic 1.8.2","pydantic 1.7.4"],"published":"2021-05-13","updated":"2026-07-08","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-5jqp-qgf6-3pvh","references":[{"url":"https://github.com/samuelcolvin/pydantic/security/advisories/GHSA-5jqp-qgf6-3pvh"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-29510"},{"url":"https://github.com/pydantic/pydantic/commit/1c24f1d74ba95ea985b50bdc001ce96c813229aa"},{"url":"https://github.com/pydantic/pydantic/commit/80e0dd3f752bef145dce12f160d262bb40ec8d47"},{"url":"https://github.com/pydantic/pydantic/commit/bdde15b7b947c94ca00fd6eb92da8db390a13520"},{"url":"https://github.com/samuelcolvin/pydantic/commit/7e83fdd2563ffac081db7ecdf1affa65ef38c468"},{"url":"https://github.com/pydantic/pydantic"},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/pydantic/PYSEC-2021-47.yaml"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/S2HT266L6Q7H6ICP7DFGXOGBJHNNKMKB"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UEFWM7DYKD2ZHE7R5YT5EQWJPV4ZKYRB"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UMKAJX4O6IGBBCE32CO2G7PZQCCQSBLV"}],"tags":["osv","pip"],"epss":0.00967,"epssPercentile":0.60161,"ingestedAt":"2026-07-08T18:25:46.029Z","slug":"CVE-2021-29510","body":"## Overview\n\nImpact\n\nPassing 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).\nPatches\n\nPydantic is be patched with fixes available in the following versions:\n\n    v1.8.2\n    v1.7.4\n    v1.6.2\n\nAll these versions are available on pypi, and will be available on conda-forge soon.\n\nSee the changelog for details.\nWorkarounds\n\nIf you absolutely can't upgrade, you can work around this risk using a validator to catch these values, brief demo:\n\nfrom datetime import date\nfrom pydantic import BaseModel, validator\n\nclass DemoModel(BaseModel):\n    date_of_birth: date\n\n    @validator('date_of_birth', pre=True)\n    def skip_infinite_values(cls, v):\n        try:\n            seconds = float(v)\n        except (ValueError, TypeError):\n            return v\n        else:\n            if seconds == float('inf'):\n                return date.max\n            elif seconds == float('-inf'):\n                return date.min\n            else:\n                return seconds\n\nNote: 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.\n\nIf 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.\nReferences\n\nThis was fixed in commit 7e83fdd.\n\n## Affected packages\n\n- `pydantic < 1.6.2`\n- `pydantic >= 1.8, < 1.8.2`\n- `pydantic >= 1.7, < 1.7.4`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `pydantic 1.6.2`\n- `pydantic 1.8.2`\n- `pydantic 1.7.4`","depth":"sunlit","depthScore":18,"depthScoreParts":{"impact":18.2,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}