Security readout for executives and security teams
Plain-English summary
CVE-2021-29510 is a denial-of-service bug in Pydantic. Certain infinity-style values supplied to date or datetime validation can make validation run indefinitely, consuming one CPU core. The business impact is service degradation where vulnerable Pydantic versions process untrusted or external date data.
Executive priority
Treat as low severity but operationally relevant for internet-facing or high-throughput Python services. Patch through normal dependency maintenance, accelerating where vulnerable date validation is exposed to external input.
Technical view
Affected Pydantic versions can enter an infinite loop when validating infinity-like inputs for date or datetime fields. The issue maps to CWE-835 and has CVSS 3.1 score 3.3. Fixed releases are v1.8.2, v1.7.4, and v1.6.2, with a validator workaround described as inferior to upgrading.
Likely exposure
Exposure is most likely in Python applications using Pydantic versions >=1.8.0 <1.8.2, >=1.7.0 <1.7.4, or <1.6.2, especially where date or datetime fields consume external data.
Exploitation context
The provided sources do not show CISA KEV listing, active exploitation, or exploit availability. Practical impact is availability loss: a crafted value reaching vulnerable validation can pin one CPU core in an infinite loop.
Researcher notes
The core condition is an infinite loop during date or datetime validation in vulnerable Pydantic branches. Sources identify fixed versions and a workaround, but do not provide evidence of active exploitation or broader affected products beyond Pydantic and downstream Fedora packaging.
Mitigation direction
- Upgrade Pydantic to v1.8.2, v1.7.4, v1.6.2, or later fixed guidance.
- Prioritize services parsing external date or datetime data through Pydantic models.
- Use vendor-recommended validators only as a temporary workaround when upgrading is impossible.
- Request vendor backport guidance if pinned to an older unsupported Pydantic branch.
- Track downstream package advisories, including Fedora updates where relevant.
Validation and detection
- Review dependency manifests, lockfiles, and SBOMs for affected Pydantic versions.
- Confirm runtime package versions in deployed Python environments and containers.
- Inventory Pydantic models with date or datetime fields fed by external data.
- Check whether patched package versions are present in build artifacts.
- Verify regression coverage for rejected invalid date and datetime inputs.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-835: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-29510 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Low
- CVSS
- 3.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L1.81.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
3.3LowVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/samuelcolvin/pydantic/security/advisories/GHSA-5jqp-qgf6-3pvhCVE reference · x_refsource_CONFIRM
- https://github.com/samuelcolvin/pydantic/commit/7e83fdd2563ffac081db7ecdf1affa65ef38c468CVE reference · x_refsource_MISC
- FEDORA-2021-f8bb3ba3ecCVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-4d3de3183fCVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-e7fabd81fbCVE reference · vendor-advisory, x_refsource_FEDORA
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Loop with Unreachable Exit Condition ('Infinite Loop')
Loop with Unreachable Exit Condition ('Infinite Loop') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.