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MongoBleed defect swirls, stamping out hope of year

criticalExploit / PoC exploited in the wildimportance 60CVE-2025-14847

Vulnerabilities mentionedAll →

CVEVulnerabilityCVSSEPSSFlagsAffectedExposurePublished
CVE-2025-14847
Unauthenticated Heap Memory Disclosure in MongoDB Server (MongoBleed)

CVE-2025-14847 ('MongoBleed') is an improper handling of length parameter inconsistency (CWE-130) in MongoDB Server's processing of Zlib-compressed protocol headers, where mismatched length fields cause the server to return uninitialized heap memory. An unauthenticated remote client can trigger the leak by sending specially crafted compressed protocol messages to a vulnerable server, with no credentials, user interaction, or complex conditions required. The impact is confidentiality-only: an attacker can harvest fragments of the server's heap memory, which may contain sensitive in-memory data such as documents, credentials, or keys, reflected in the High confidentiality rating in the 8.7 CVSS 4.0 score. Virtually every MongoDB Server release from 3.6 through 8.2 is affected unless updated to the fixed patch levels (e.g., 8.2.3, 8.0.17, 7.0.28, 6.0.27, 5.0.32, 4.4.30), so the potentially exposed population is extremely large. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2025-12-29, is reported as actively exploited in the wild worldwide (including a joint US-Australia advisory), and carries a very high EPSS of 83.2%, making patching urgent.

Do: Upgrade MongoDB Server immediately to the fixed release for your branch: 8.2.3+, 8.0.17+, 7.0.28+, 6.0.27+, 5.0.32+, or 4.4.30+; 3.6, 4.0, and 4.2 deployments are affected in all versions and should be moved to a patched release or retired per MongoDB guidance. Until patched, restrict network access to MongoDB to trusted clients and consider disabling Zlib network compression as an interim mitigation, and review logs for unauthenticated client connections. Because the flaw is on CISA's KEV catalog with active exploitation observed (including ransomware-adjacent tracking), apply mitigations per BOD 22-01 timelines or discontinue use of affected unpatched instances.

8.783% KEV PoC ×3
  • MongoDB Server 8.2 versions prior to 8.2.3
  • MongoDB Server 8.0 versions prior to 8.0.17
  • MongoDB Server 7.0 versions prior to 7.0.28
  • +6 more
masstens of thousands of MongoDB instances directly exposed to the internet, within millions of total deployments worldwide (estimate)
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The high-severity vulnerability is under active exploitation and affects many versions of MongoDB, a nearly ubiquitous open-source database.

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Abstract binary code rippling on waving ribbons. (Getty Images)

Cybersecurity professionals are closing out 2025 confronting yet another information-disclosure vulnerability, drawing widespread concern as threat hunters and researchers race to avoid impacts comparable to previous defects dubbed with a “bleed” suffix. 

MongoBleed — CVE-2025-14847 — is a high-severity vulnerability affecting many versions of MongoDB with default configurations that allows unauthenticated attackers to leak server memory, which could contain sensitive data including credentials or tokens. MongoDB disclosed the vulnerability Dec. 19 and worries escalated when a public proof of concept was released Dec. 26.

Multiple cybersecurity firms report the vulnerability is under active exploitation in the wild, and the Cybersecurity and Infrastructure Security Agency added the defect to its known exploited vulnerabilities catalog Monday. 

MongoDB is a nearly ubiquitous open-source database. Researchers at Wiz said 42% of cloud environments contain at least one instance of a MongoDB version vulnerable to CVE-2025-14847, including publicly exposed and internal resources. 

Shadowserver scans found almost 75,000 possibly unpatched versions of MongoDB, out of nearly 79,000 publicly exposed instances Monday. Censys said it observed more than 87,000 potentially vulnerable instances of MongoDB on Saturday. 

Countries with the highest concentration of exposed instances potentially at risk of compromise include China, the United States, Germany, France, Hong Kong, India and Singapore.

The defect, which has a CVSS rating of 8.7, is “concerning because of the scale of the install base, ease of exploitation and lack of forensic evidence left behind,” Ben Read, director of strategic threat intelligence at Wiz, told CyberScoop. “Because it’s a memory-leak vulnerability, there isn’t malware left on the disk, or any durable forensic evidence that data was accessed.”

Wiz has observed exploitation attempts and evidence of active exploitation, but hasn’t been able to attribute any of that malicious activity to a specific threat group, Read said. “We expect that it is being exploited by a wide variety of actors, based on past precedent.”

While threat hunters are on high alert, key details about attacks and the potential impact for exploitation at scale is limited.

“Real-world attack details have been oddly lacking so far,” Caitlin Condon, vice president of research at VulnCheck, told CyberScoop. 

“A lot of the current public info corpus on MongoBleed seems to be assuming that because there’s public proof of concept, exploitation is trivial, but an adversary still has to be able to get useful data out of an attack flow. I’m not sure it’s actually clear yet that that’s trivial,” she added.

Yet, attacker interest in the vulnerability is growing. As of Monday, VulnCheck is tracking more than a dozen public proof of concepts, some of which appear to be valid. 

MongoDB urges customers to upgrade to a patched version as soon as possible, noting that the potential impact is expansive with vulnerable versions dating back to 2017.

Downtime around the holidays may also be impacting visibility and delaying efforts to triage and hunt for evidence of compromise.

“Many security teams are likely to have reduced capacity this week, which may contribute to a longer tail on observed exploitation details and threat actor attribution,” Condon said.

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