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Vulnerabilities

Vulnerability · CVE-2026-96749

PyMongo: PYTHON-5996 Heap out-of-bounds write via signed size overflow in BSON document encoding

Published Oct 5, 2026 · catalog updated Oct 15, 2026 · PyMongo: PYTHON-5996 Heap out-of-bounds

Check if you run it

No confirmed exploitation is on record for CVE-2026-96749. EPSS is 0.13%. Act only if a listed version of PyMongo: PYTHON-5996 Heap out-of-bounds is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (PyMongo: PYTHON-5996 Heap out-of-bounds).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.4
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.13%
Remediation
Advisory link
Affected products
PyPI pymongo

An integer overflow in the BSON document encoding component of the MongoDB Python Driver's bundled native extension may occur when a single document is built from an unusually large amount of caller-supplied data. Size arithmetic is performed in a signed 32-bit type, and the guard meant to catch the overflow is written in a form whose behavior is not defined by the C language standard. A party with no privileges who can place a very large value into data that an application encodes may, depending on how the native extension was built, cause a write outside the bounds of an allocated buffer inside the application's own process.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • PyPI pymongo0 → 4.18.2

How to fix CVE-2026-96749

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-96749. EPSS is 0.13%. Act only if a listed version of PyMongo: PYTHON-5996 Heap out-of-bounds is installed.

Which versions are affected?

Compare what you have installed with 0 → 4.18.2. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-190: Integer Overflow. EPSS 0.13%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 5, 2026 · GitHub Advisory Database

    Detected

    An integer overflow in the BSON document encoding component of the MongoDB Python Driver's bundled native extension may occur when a single document is built from an unusually large amount of caller-supplied data. Size arithmetic is performed in a signed 32-bit type, and the guard meant to catch the overflow is written in a form whose behavior is not defined by the C language standard. A party wit

  2. Oct 6, 2026 · GitHub Advisory Database

    Fix available

    pymongo fixed in 4.18.2

  3. Oct 6, 2026 · GitHub Advisory Database

    Fix available

    pymongo fixed in 4.18.2

  4. Oct 6, 2026 · GitHub Advisory Database

    Updated

    An integer overflow in the BSON document encoding component of the MongoDB Python Driver's bundled native extension may occur when a single document is built from an unusually large amount of caller-supplied data. Size arithmetic is performed in a signed 32-bit type, and the guard meant to catch the overflow is written in a form whose behavior is not defined by the C language standard. A party wit

  5. Oct 15, 2026 · GitHub Advisory Database

    Updated

    An integer overflow in the BSON document encoding component of the MongoDB Python Driver's bundled native extension may occur when a single document is built from an unusually large amount of caller-supplied data. Size arithmetic is performed in a signed 32-bit type, and the guard meant to catch the overflow is written in a form whose behavior is not defined by the C language standard. A party wit

Sources

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.