CVE-2026-84970
Heap over-read or silent misparse via 32-bit truncation of JSON length in BSON JSON parser
A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's BSON library. An actor who controls the text that an embedding application hands to the library's public JSON parsing interface, when that text is very large, can cause the library to read memory beyond the supplied buffer and return it to the caller, to silently accept only part of the input as a complete document, or to terminate the process. No MongoDB server, credentials, or non-default configuration is required; the effect is confined to the process that uses the library.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
5.9
Heap over-read or silent misparse via 32-bit truncation of JSON length in BSON JSON parser
A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's BSON library. An actor who controls the text that an embedding application hands to the library's public JSON parsing interface, when that text is very large, can cause the library to read memory beyond the supplied buffer and return it to the caller, to silently accept only part of the input as a complete document, or to terminate the process. No MongoDB server, credentials, or non-default configuration is required; the effect is confined to the process that uses the library.
- Record
CVE-2026-84970- CVSS 4.0
- 5.9 Medium
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N - CVSS 3.1
- 6.2 Medium
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H - Weakness
- CWE-681
- Updated
- 2026-11-02
EUVDEUVD-2026-70505
5.9
A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's BSON library. An actor who controls the text that an embedding application hands to the library's public JSON parsing interface, when that text is very large, can cause the library to read memory beyond the supplied buffer and return it to the caller, to silently accept only part of the input as a complete document, or to terminate the process. No MongoDB server, credentials, or non-default configuration is required; the effect is confined to the process that uses the library.
- Record
EUVD-2026-70505- CVSS 4.0
- 5.9 Medium
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-j94p-2ppx-483m
5.9
A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's...
A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's BSON library. An actor who controls the text that an embedding application hands to the library's public JSON parsing interface, when that text is very large, can cause the library to read memory beyond the supplied buffer and return it to the caller, to silently accept only part of the input as a complete document, or to terminate the process. No MongoDB server, credentials, or non-default configuration is required; the effect is confined to the process that uses the library.
- Record
GHSA-j94p-2ppx-483m- CVSS 4.0
- 5.9 Medium
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 6.2 Medium
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H - Weakness
- CWE-681
- Updated
- 2026-11-02
NVD
5.9
A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's BSON library. An actor who controls the text that an embedding application hands to the library's public JSON parsing interface, when that text is very large, can cause the library to read memory beyond the supplied buffer and return it to the caller, to silently accept only part of the input as a complete document, or to terminate the process. No MongoDB server, credentials, or non-default configuration is required; the effect is confined to the process that uses the library.
- Record
CVE-2026-84970- CVSS 4.0
- 5.9 Medium
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 6.2 Medium
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H - CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H - Weakness
- CWE-681
- Updated
- 2026-11-02
OSV
5.9
Heap over-read or silent misparse via 32-bit truncation of JSON length in BSON JSON parser
A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's BSON library. An actor who controls the text that an embedding application hands to the library's public JSON parsing interface, when that text is very large, can cause the library to read memory beyond the supplied buffer and return it to the caller, to silently accept only part of the input as a complete document, or to terminate the process. No MongoDB server, credentials, or non-default configuration is required; the effect is confined to the process that uses the library.
- Record
CVE-2026-84970- CVSS 4.0
- 5.9 Medium
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N - Weakness
- CWE-681
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-84970
5.8
A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's BSON library. An actor who controls the text that an embedding application hands to the library's public JSON parsing interface, when that text is very large, can cause the library to read memory beyond the supplied buffer and return it to the caller, to silently accept only part of the input as a complete document, or to terminate the process. No MongoDB server, credentials, or non-default configuration is required; the effect is confined to the process that uses the library.
- Record
DEBIAN-CVE-2026-84970- CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-84970
5.9
A numeric truncation weakness exists in the JSON parsing component of the MongoDB C++ Driver's BSON library. An actor who controls the text that an embedding application hands to the library's public JSON parsing interface, when that text is very large, can cause the library to read memory beyond the supplied buffer and return it to the caller, to silently accept only part of the input as a complete document, or to terminate the process. No MongoDB server, credentials, or non-default configuration is required; the effect is confined to the process that uses the library.
- Record
UBUNTU-CVE-2026-84970- CVSS 4.0
- 5.9 Medium
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N - CVSS 3.1
- 5.8 Medium
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H - CVSS 3.1
- 6.2 Medium
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
mongo-cxx-driverDebian:14 |
before 4.5.2-1, plus listed versions 3.10.1-13.10.2-13.11.0-13.4.1-13.6.0-1 Show 16 moreShow less3.6.1-13.6.2-13.6.3-13.6.5-13.6.6-13.6.7-13.7.0-13.7.1-13.8.0-13.8.1-13.9.0-14.0.0-14.1.4-14.4.0-14.5.0-14.5.1-1 |
4.5.2-1 |
mongo-cxx-driverUbuntu:26.10 |
All versions, plus listed versions 4.4.0-14.5.0-1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-84970 is a medium vulnerability (CVSS 5.9) in Mongodb C++ Driver, published September 3, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.12%, the 2nd percentile. Fixed in mongo-cxx-driver 4.5.2-1.
References
jira.mongodb.org/browse/CXX-3547
nvd.nist.gov/vuln/detail/CVE-2026-84970
github.com/advisories/GHSA-j94p-2ppx-483m
github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84970.json
security-tracker.debian.org/tracker/CVE-2026-84970
ubuntu.com/security/CVE-2026-84970
cve.org/CVERecord?id=CVE-2026-84970