AI Threat AlertCVE-2026-18743: popt: heap corruption via config parsing causes local DoS
LOWA flaw in the popt command-line parsing library lets specially crafted configuration content corrupt heap metadata when it is loaded, because `poptConfigFileToString` reallocates its buffers incorrectly (CWE-131). The impact is limited to a local denial of service. The CVSS score is 2.5 (low), and the attack needs local access, low privileges and high complexity. It is not in CISA KEV, no public exploit or Nuclei template exists, and EPSS and SSVC data are not yet available. The AI relevance comes from reach rather than severity. popt is a base-OS dependency that ships inside about 35 Red Hat OpenShift AI (rhoai) container images, including MLflow, KServe, Ray operators and model-registry components, and 695 downstream dependents are tracked. Apply the Red Hat update (RHSA-2026:56984) through your normal patch cycle and rebuild or pull refreshed OpenShift AI images. Treat it as routine hygiene, not an emergency.
What is the risk?
Low overall risk. The CVSS vector (AV:L/AC:H/PR:L) means an attacker needs a foothold on the host or the ability to supply config content that a popt-using process loads. Impact is limited to availability (A:L), with no confidentiality or integrity impact, and the vendor describes only a small memory corruption. There is no known exploitation, no public PoC and no KEV listing. The package risk context (OpenSSF 5.4/10, 142 other CVEs, 695 dependents) raises the importance of keeping base images current, but not the urgency of this particular flaw.
How does the attack unfold?
What systems are affected?
How severe is it?
What is the attack surface?
What should I do?
1 step1) Apply Red Hat advisory RHSA-2026:56984 and update the popt package on hosts and in RHEL-based images. 2) Rebuild or pull refreshed rhoai/* and openshift/ose-rhel-coreos images once patched versions are published, and restart the affected pods and nodes. 3) Restrict who can write or modify configuration files that popt-based tools read, and enforce least privilege on nodes and containers. 4) Detect by scanning image inventories (SBOM or vulnerability scanner) for vulnerable popt versions and by monitoring for unexpected crashes or segfaults in popt-linked processes. 5) Track the Red Hat CVE page and Bugzilla 2510809 for fixed version numbers, since affected and patched ranges are not yet listed in the data.
How is it classified?
Which compliance frameworks are affected?
This CVE is relevant to:
Frequently Asked Questions
What is CVE-2026-18743?
A flaw in the popt command-line parsing library lets specially crafted configuration content corrupt heap metadata when it is loaded, because `poptConfigFileToString` reallocates its buffers incorrectly (CWE-131). The impact is limited to a local denial of service. The CVSS score is 2.5 (low), and the attack needs local access, low privileges and high complexity. It is not in CISA KEV, no public exploit or Nuclei template exists, and EPSS and SSVC data are not yet available. The AI relevance comes from reach rather than severity. popt is a base-OS dependency that ships inside about 35 Red Hat OpenShift AI (rhoai) container images, including MLflow, KServe, Ray operators and model-registry components, and 695 downstream dependents are tracked. Apply the Red Hat update (RHSA-2026:56984) through your normal patch cycle and rebuild or pull refreshed OpenShift AI images. Treat it as routine hygiene, not an emergency.
Is CVE-2026-18743 actively exploited?
No confirmed active exploitation of CVE-2026-18743 has been reported, but organizations should still patch proactively.
How to fix CVE-2026-18743?
1) Apply Red Hat advisory RHSA-2026:56984 and update the popt package on hosts and in RHEL-based images. 2) Rebuild or pull refreshed rhoai/* and openshift/ose-rhel-coreos images once patched versions are published, and restart the affected pods and nodes. 3) Restrict who can write or modify configuration files that popt-based tools read, and enforce least privilege on nodes and containers. 4) Detect by scanning image inventories (SBOM or vulnerability scanner) for vulnerable popt versions and by monitoring for unexpected crashes or segfaults in popt-linked processes. 5) Track the Red Hat CVE page and Bugzilla 2510809 for fixed version numbers, since affected and patched ranges are not yet listed in the data.
What systems are affected by CVE-2026-18743?
This vulnerability affects the following AI/ML architecture patterns: model serving, ML platform operators (Kubernetes/OpenShift), training pipelines, ML experiment tracking and model registries, notebook and workbench environments.
What is the CVSS score for CVE-2026-18743?
CVE-2026-18743 has a CVSS v3.1 base score of 2.5 (LOW).
What is the AI security impact?
Affected AI Architectures
MITRE ATLAS Techniques
AML.T0010.001AI SoftwareAML.T0029Denial of AI ServiceCompliance Controls Affected
What are the technical details?
Original Advisory
A flaw was found in popt. This vulnerability allows an attacker to provide specially crafted configuration content to a host, which, when loaded, can lead to a small memory corruption issue. This occurs because of an error in how the `poptConfigFileToString` function reallocates memory for buffers. Successful exploitation could result in heap metadata corruption, potentially causing the affected process to become unavailable (denial of service).
Exploitation Scenario
An attacker with low-privilege local access to a node or container in an ML platform (for example, a compromised data scientist notebook workload) places a malformed configuration file in a path read by a popt-based utility or operator process. When the process loads the file, `poptConfigFileToString` mishandles the buffer reallocation, corrupts heap metadata and crashes the process. The result is a brief availability loss for that component, such as a controller restart that delays model deployment or pipeline reconciliation. The high attack complexity and the limited impact make this a nuisance-level scenario rather than a path to compromise.
Weaknesses (CWE)
CWE-131 — Incorrect Calculation of Buffer Size: The product does not correctly calculate the size to be used when allocating a buffer.
- [Implementation] When allocating a buffer for the purpose of transforming, converting, or encoding an input, allocate enough memory to handle the largest possible encoding. For example, in a routine that converts "&" characters to "&" for HTML entity encoding, the output buffer needs to be at least 5 times as large as the input buffer.
- [Implementation] Understand the programming language's underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, "not-a-number" calculations, and how the language handles numbers that are too large or too small for its underlying representation. [REF-7] Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.
Source: MITRE CWE corpus.
CVSS Vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:LReferences
- access.redhat.com/errata/RHSA-2026:56984vendor-advisoryx_refsource_REDHAT
- access.redhat.com/security/cve/CVE-2026-18743vdb-entryx_refsource_REDHAT
- bugzilla.redhat.com/show_bug.cgiissue-trackingx_refsource_REDHAT
Timeline
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