VulnerabilityPublished 17 Mar 2026

CVE-2026-4147: MongoDB Server · Use of Uninitialized Variable

Affects MongoDB ServerSource CVE Database V5

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Not known to be exploited · CVSS 7.1 High · fixed in 8.2.6 : patch MongoDB Server soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score

7.1High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 8.2.6, 8.0.20, 7.0.31

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: High
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: High: There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 17 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade MongoDB Server to 8.2.6, 8.0.20 or 7.0.31.

Affected software

Product	Affected	Fixed in
MongoDB IncMongoDB Server	Affected >=8.2 <8.2.6	Fixed in 8.2.6
MongoDB IncMongoDB Server	Affected >=8.0 <8.0.20	Fixed in 8.0.20
MongoDB IncMongoDB Server	Affected >=7.0 <7.0.31	Fixed in 7.0.31

AI-suggested

Monitor MongoDB usage logs for unusual or excessive filemd5 command invocations, especially from users with read roles.
Restrict read role assignments strictly to trusted and necessary users; implement the principle of least privilege.
4. Consider implementing network segmentation and access controls to limit exposure of MongoDB instances to only authorized systems and users. 5. Use encryption at rest and in transit to reduce the impact of any leaked data. 6. Conduct regular audits of user permissions and review authentication mechanisms to detect and prevent unauthorized access. 7. Employ runtime application self-protection (RASP) or database activity monitoring tools that can detect anomalous command usage patterns. 8. If patching is delayed, consider disabling or restricting the filemd5 command usage via MongoDB configuration or role-based access control where feasible.

Description

An authenticated user with the read role may read limited amounts of uninitialized stack memory via specially-crafted issuances of the filemd5 command.

Impact

The primary impact of CVE-2026-4147 is unauthorized disclosure of sensitive information through leakage of uninitialized stack memory. This can compromise confidentiality by exposing internal server data that might include cryptographic material or application secrets. Attackers with read access can leverage this information to escalate privileges, bypass security controls, or conduct targeted attacks against the affected systems. Since the vulnerability requires only read role authentication, any compromised or insider account with read permissions is sufficient to exploit it. This broadens the attack surface, especially in environments with multiple users or third-party integrations. Although integrity and availability are not directly affected, the confidentiality breach can lead to significant downstream risks, including data breaches and regulatory non-compliance. Organizations relying heavily on MongoDB for critical data storage, especially in sectors like finance, healthcare, and government, face increased risk. The lack of known exploits currently reduces immediate threat but does not eliminate the potential for future weaponization.

CWE-457Use of Uninitialized Variable (opens in a new tab)
Variant weaknessLikelihood of exploit: High
The code uses a variable that has not been initialized, leading to unpredictable or unintended results.
Implementation · Attack Surface Reduction
Ensure that critical variables are initialized before first use.
Build and Compilation · Compilation or Build Hardening
Most compilers will complain about the use of uninitialized variables if warnings are turned on.
Implementation · Operation
When using a language that does not require explicit declaration of variables, run or compile the software in a mode that reports undeclared or unknown variables. This may indicate the presence of a typographic error in the variable's name.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

jira.mongodb.org/browse/SERVER-119317 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Mar 2026, 18:28 UTC

WeaknessesCWE-457

Technical details

References

Community reviews

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