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CVE-2026-84969

Heap overflow via truncated base64 encoding of binary fields in length-limited JSON output

6.3 MediumFix available

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
None

Exploit likelihood

0.27%Up 0.1 points since Sep 4, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.3

Heap overflow via truncated base64 encoding of binary fields in length-limited JSON output

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.

Record
CVE-2026-84969
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
3.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-787
Updated
2026-11-02
EUVDEUVD-2026-70508 6.3

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.

Record
EUVD-2026-70508
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-9xr7-hhfx-wh4c 6.3

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write...

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.

Record
GHSA-9xr7-hhfx-wh4c
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/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
3.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-787
Updated
2026-11-02
NVD 6.3

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.

Record
CVE-2026-84969
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/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
3.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
CVSS 3.1
3.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-787
Updated
2026-11-02
OSVALPINE-CVE-2026-84969 3.7

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.

Record
ALPINE-CVE-2026-84969
CVSS 3.1
3.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Updated
2026-11-03
OSV 6.3

Heap overflow via truncated base64 encoding of binary fields in length-limited JSON output

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.

Record
CVE-2026-84969
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-787
Updated
2026-11-02
Show 7 moreShow less
OSVDEBIAN-CVE-2026-84969 3.7

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.

Record
DEBIAN-CVE-2026-84969
CVSS 3.1
3.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Updated
2026-11-02
OSVOESA-2026-4352 6.3

mongo-c-driver security update

mongo-c-driver is a project that includes two libraries: libmongoc, a client library written in C for MongoDB. libbson, a library providing useful routines related to building, parsing, and iterating BSON documents.

Security Fix(es):

A weakness in the MongoDB C Driver allows special elements in caller-supplied database and collection name components to pass without sanitization when the driver composes the target namespace for an operation. An application that incorporates untrusted input into these name components can have operations directed at a resource other than the one intended.(CVE-2026-81524)

An incorrect numeric conversion in the JSON parsing component of the MongoDB C Driver's BSON library may cause an unusually large text value to be silently shortened, or the corresponding field to be omitted, while the parsing operation still reports success and returns no error. An unauthenticated party who can supply the input processed by an application that uses this component may cause that application to hold data that does not match what was submitted, which may result in unintended alteration of data.(CVE-2026-84963)

A double free in the OpenSSL-based TLS certificate revocation checking path of the MongoDB C Driver can be reached by a TLS endpoint that the client already trusts. During the handshake, specially formed certificate data can cause the same heap object to be released twice. An unauthenticated party acting as the trusted endpoint may cause the connecting client application to terminate unexpectedly.(CVE-2026-84964)

An integer wraparound in an allocation size calculation in the BSON library's JSON parsing code can cause a buffer to be released while a following copy operation still writes through the stale pointer. On builds where sizes are 32 bits, an unauthenticated party able to supply a sufficiently large JSON input to an application that links the library may cause that application to terminate unexpectedly, resulting in denial of service.(CVE-2026-84965)

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.(CVE-2026-84969)

Record
OESA-2026-4352
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
OSVOESA-2026-4353 6.3

mongo-c-driver security update

mongo-c-driver is a project that includes two libraries: libmongoc, a client library written in C for MongoDB. libbson, a library providing useful routines related to building, parsing, and iterating BSON documents.

Security Fix(es):

A weakness in the MongoDB C Driver allows special elements in caller-supplied database and collection name components to pass without sanitization when the driver composes the target namespace for an operation. An application that incorporates untrusted input into these name components can have operations directed at a resource other than the one intended.(CVE-2026-81524)

An incorrect numeric conversion in the JSON parsing component of the MongoDB C Driver's BSON library may cause an unusually large text value to be silently shortened, or the corresponding field to be omitted, while the parsing operation still reports success and returns no error. An unauthenticated party who can supply the input processed by an application that uses this component may cause that application to hold data that does not match what was submitted, which may result in unintended alteration of data.(CVE-2026-84963)

A double free in the OpenSSL-based TLS certificate revocation checking path of the MongoDB C Driver can be reached by a TLS endpoint that the client already trusts. During the handshake, specially formed certificate data can cause the same heap object to be released twice. An unauthenticated party acting as the trusted endpoint may cause the connecting client application to terminate unexpectedly.(CVE-2026-84964)

An integer wraparound in an allocation size calculation in the BSON library's JSON parsing code can cause a buffer to be released while a following copy operation still writes through the stale pointer. On builds where sizes are 32 bits, an unauthenticated party able to supply a sufficiently large JSON input to an application that links the library may cause that application to terminate unexpectedly, resulting in denial of service.(CVE-2026-84965)

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.(CVE-2026-84969)

Record
OESA-2026-4353
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
OSVOESA-2026-4354 6.3

mongo-c-driver security update

mongo-c-driver is a project that includes two libraries: libmongoc, a client library written in C for MongoDB. libbson, a library providing useful routines related to building, parsing, and iterating BSON documents.

Security Fix(es):

A weakness in the MongoDB C Driver allows special elements in caller-supplied database and collection name components to pass without sanitization when the driver composes the target namespace for an operation. An application that incorporates untrusted input into these name components can have operations directed at a resource other than the one intended.(CVE-2026-81524)

An incorrect numeric conversion in the JSON parsing component of the MongoDB C Driver's BSON library may cause an unusually large text value to be silently shortened, or the corresponding field to be omitted, while the parsing operation still reports success and returns no error. An unauthenticated party who can supply the input processed by an application that uses this component may cause that application to hold data that does not match what was submitted, which may result in unintended alteration of data.(CVE-2026-84963)

A double free in the OpenSSL-based TLS certificate revocation checking path of the MongoDB C Driver can be reached by a TLS endpoint that the client already trusts. During the handshake, specially formed certificate data can cause the same heap object to be released twice. An unauthenticated party acting as the trusted endpoint may cause the connecting client application to terminate unexpectedly.(CVE-2026-84964)

An integer wraparound in an allocation size calculation in the BSON library's JSON parsing code can cause a buffer to be released while a following copy operation still writes through the stale pointer. On builds where sizes are 32 bits, an unauthenticated party able to supply a sufficiently large JSON input to an application that links the library may cause that application to terminate unexpectedly, resulting in denial of service.(CVE-2026-84965)

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.(CVE-2026-84969)

Record
OESA-2026-4354
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
OSVOESA-2026-4355 6.3

mongo-c-driver security update

mongo-c-driver is a project that includes two libraries: libmongoc, a client library written in C for MongoDB. libbson, a library providing useful routines related to building, parsing, and iterating BSON documents.

Security Fix(es):

A weakness in the MongoDB C Driver allows special elements in caller-supplied database and collection name components to pass without sanitization when the driver composes the target namespace for an operation. An application that incorporates untrusted input into these name components can have operations directed at a resource other than the one intended.(CVE-2026-81524)

An incorrect numeric conversion in the JSON parsing component of the MongoDB C Driver's BSON library may cause an unusually large text value to be silently shortened, or the corresponding field to be omitted, while the parsing operation still reports success and returns no error. An unauthenticated party who can supply the input processed by an application that uses this component may cause that application to hold data that does not match what was submitted, which may result in unintended alteration of data.(CVE-2026-84963)

A double free in the OpenSSL-based TLS certificate revocation checking path of the MongoDB C Driver can be reached by a TLS endpoint that the client already trusts. During the handshake, specially formed certificate data can cause the same heap object to be released twice. An unauthenticated party acting as the trusted endpoint may cause the connecting client application to terminate unexpectedly.(CVE-2026-84964)

An integer wraparound in an allocation size calculation in the BSON library's JSON parsing code can cause a buffer to be released while a following copy operation still writes through the stale pointer. On builds where sizes are 32 bits, an unauthenticated party able to supply a sufficiently large JSON input to an application that links the library may cause that application to terminate unexpectedly, resulting in denial of service.(CVE-2026-84965)

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.(CVE-2026-84969)

Record
OESA-2026-4355
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
OSVUBUNTU-CVE-2026-84969 6.3

A memory-handling error in the BSON-to-JSON conversion helpers of the MongoDB C Driver can write a small number of bytes past the end of a heap buffer when a binary field is encoded and the output is cut short at a caller-configured length limit. A party who supplies the document content, with no privileges on the application that links the driver, may cause a small amount of data outside the intended buffer to be altered.

Record
UBUNTU-CVE-2026-84969
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
3.7 LowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Updated
2026-11-02
OSVopenSUSE-SU-2026:11706-1 No score

bson-devel-2.5.2-1.1 on GA media

These are all security issues fixed in the bson-devel-2.5.2-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:11706-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
mongo-c-driver
Alpine:v3.24
before 1.30.14-r0
1.30.14-r0
mongo-c-driver
Debian:13
All versions, plus listed versions
1.30.4-11.30.4-1+deb13u11.30.4-1+deb13u21.30.4-1+deb13u32.0.2-1
Show 18 moreShow less
2.1.0-12.1.1-12.1.2-12.2.0-12.2.1-12.2.2-12.2.3-12.2.4-12.3.0-12.3.1-12.3.2-12.3.3-12.4.0-12.5.0-12.5.1-12.5.2-12.5.3-12.5.5-1
None known
mongo-c-driver
Debian:14
before 2.5.2-1, plus listed versions
1.30.4-12.0.2-12.1.0-12.1.1-12.1.2-1
Show 12 moreShow less
2.2.0-12.2.1-12.2.2-12.2.3-12.2.4-12.3.0-12.3.1-12.3.2-12.3.3-12.4.0-12.5.0-12.5.1-1
2.5.2-1
mongo-c-driver
openEuler:22.03-LTS-SP4
From an advisory covering 5 CVEs
before 1.30.9-1.oe2203sp4
1.30.9-1.oe2203sp4
mongo-c-driver
openEuler:24.03-LTS-SP1
From an advisory covering 5 CVEs
before 1.30.9-1.oe2403sp1
1.30.9-1.oe2403sp1
mongo-c-driver
openEuler:24.03-LTS-SP3
From an advisory covering 5 CVEs
before 1.30.9-1.oe2403sp3
1.30.9-1.oe2403sp3
mongo-c-driver
openEuler:24.03-LTS-SP4
From an advisory covering 5 CVEs
before 1.30.9-1.oe2403sp4
1.30.9-1.oe2403sp4
mongo-c-driver
Ubuntu:Pro:20.04:LTS
All versions, plus listed versions
1.15.0-11.15.1-11.15.2-11.16.0-11.16.1-11.16.1-1build11.16.1-1build21.16.1-1ubuntu0.1~esm1
None known
mongo-c-driver
Ubuntu:Pro:22.04:LTS
All versions, plus listed versions
1.18.0-11.19.1-11.19.2-11.20.0-11.20.0-1build1
Show 4 moreShow less
1.20.1-11.21.0-11.21.0-1build11.21.0-1ubuntu0.1~esm1
None known
mongo-c-driver
Ubuntu:Pro:24.04:LTS
All versions, plus listed versions
1.24.3-11.24.4-11.25.1-11.25.2-11.25.4-1
Show 4 moreShow less
1.26.0-11.26.0-1.1ubuntu11.26.0-1.1ubuntu21.26.0-1.1ubuntu2+esm1
None known
mongo-c-driver
Ubuntu:26.10
All versions, plus listed versions
2.2.2-12.3.1-12.3.2-12.3.3-1build12.5.0-1
None known
mongo-c-driver
Ubuntu:26.04:LTS
All versions, plus listed versions
1.30.4-1ubuntu12.2.0-12.2.1-12.2.2-1
None known
mongo-c-driver
openSUSE:Tumbleweed
From an advisory covering 4 CVEs
before 2.5.2-1.1
2.5.2-1.1

History

History
RecordedChangedSources
affected, facts
affected, aliases, referencesOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-84969 is a medium vulnerability (CVSS 6.3) 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 0.27%, the 19th percentile. Fixed in mongo-c-driver 1.30.14-r0.

References

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