CVE-2026-93318
Description
A flaw was found in BuildKit. A remote attacker can supply a crafted container image that advertises layer identifiers matching another image without containing the actual layer contents. Because BuildKit does not validate that these identifiers match the layer data before caching them, a shared build daemon can store the attacker's layers under the identity of a legitimate image. As a result, subsequent builds using the legitimate image may execute arbitrary attacker-controlled code, allowing the attacker to steal build secrets or tamper with build artifacts.
Statement
A flaw was found in BuildKit's snapshot and cache identity derivation mechanism. When processing a container image, BuildKit fails to validate advertised DiffIDs against actual uncompressed layer contents. A remote attacker can provide a crafted image with spoofed DiffIDs to poison a shared daemon cache. Subsequent builds referencing legitimate base images can inadvertently mount attacker-controlled layers, leading to arbitrary code execution during the build lifecycle, compromise of mounted secrets, and manipulation of output artifacts.
Mitigation
Avoid sharing persistent BuildKit daemon cache instances across multi-tenant or untrusted build workloads, and isolate builder runners per tenant. Regularly prune daemon cache and restrict image pull access to verified, trusted registries.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | High | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | Required | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | High | N/A | N/A |
| Integrity Impact | High | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity,Other
Technical Impact: Modify Application Data; Other
Integrity checks usually use a secret key that helps authenticate the data origin. Skipping integrity checking generally opens up the possibility that new data from an invalid source can be injected.
Integrity,Other
Technical Impact: Other
Data that is parsed and used may be corrupted.
Non-Repudiation,Other
Technical Impact: Hide Activities; Other
Without a checksum check, it is impossible to determine if any changes have been made to the data after it was sent.
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