CVE-2026-48702
Description
A flaw was found in Rekor. The Package.Unmarshal() function, which processes Alpine Package Keep (APK) files, decompresses gzip streams without limiting the total decompressed size. A remote attacker can exploit this by crafting a malicious APK file with a high compression ratio, causing the server to consume excessive memory. This leads to a Denial of Service (DoS) through an out-of-memory (OOM) error, and can be triggered via unauthenticated API endpoints.
Statement
A flaw was found in Rekor, a transparency log for supply chain security. The Alpine APK parsing logic decompresses gzip members without bounding total decompressed size, allowing a decompression bomb to cause out-of-memory conditions via unauthenticated API endpoints. This vulnerability is server-side only, affecting the Rekor server's APK entry processing. Products that import github.com/sigstore/rekor as a Go client library are not affected, as the vulnerable code path (Package.Unmarshal in pkg/types/alpine/apk.go) is only reachable through the Rekor server's HTTP API handlers.
Mitigation
There is no effective workaround. Setting max_request_body_size reduces but does not eliminate exposure due to the ~1000:1 compression ratio (a 1MB body limit still allows ~1GB heap allocation). Setting max_apk_metadata_size has no effect on this vulnerability since the check is applied after decompression.
Upgrade to Rekor 1.5.2 or later.
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).
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 | Low | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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