CVE-2026-48702: 
Datadog Agent vulnerability analysis and mitigation

CVE-2026-48702 is a denial-of-service vulnerability in Sigstore Rekor, a software supply chain transparency log, caused by unbounded gzip decompression during Alpine APK package parsing. The Package.Unmarshal() function in pkg/types/alpine/apk.go decompresses APK gzip members into in-memory buffers without any size cap, enabling a decompression bomb attack. It affects Rekor versions >= 0.3.0 and < 1.5.2, and was first published on May 26, 2026, with the advisory added to the GitHub Advisory Database on June 25, 2026. The vulnerability carries a CVSS v3.1 base score of 7.5 (High) (GitHub Advisory, Sigstore Advisory).

The root cause is CWE-770 (Allocation of Resources Without Limits or Throttling): the Package.Unmarshal() function decompresses both the signature and control gzip members of an APK file into heap memory with no bound on total decompressed size. The existing max_apk_metadata_size check (default 1 MB) is applied only to individual tar entry header sizes after decompression completes, so it provides no protection against a decompression bomb. An attacker can craft a gzip stream with approximately a 1000:1 compression ratio (e.g., 2 MB of compressed zeros expanding to ~2 GB), submit it as spec.package.content in an Alpine ProposedEntry, and trigger a fatal Go runtime out-of-memory error or OS OOM-kill that bypasses the server's recover() middleware. The attack is reachable via two unauthenticated HTTP endpoints — POST /api/v1/log/entries (createLogEntry) and POST /api/v1/log/entries/retrieve (searchLogQuery) — both of which invoke the call chain V001Entry.Canonicalize() → fetchExternalEntities() → apk.Unmarshal(packageData) (GitHub Advisory, Sigstore Advisory).

Successful exploitation causes a fatal out-of-memory condition on the Rekor server, resulting in a complete availability loss — either a Go runtime crash or an OS-level OOM-kill — that cannot be caught by the server's error recovery middleware. Because Rekor serves as a transparency log for software supply chain artifacts, its unavailability can disrupt signature verification workflows and artifact integrity checks for dependent CI/CD pipelines and package consumers. There is no confidentiality or integrity impact; the vulnerability is purely a denial-of-service (GitHub Advisory).

The vulnerability is exploitable by unauthenticated remote attackers with low attack complexity, requiring no user interaction, making it highly automatable. No public proof-of-concept exploit code has been identified, and there is no evidence of in-the-wild exploitation at this time; the NVD SSVC assessment lists exploitation as "none" (Feedly). The EPSS score is approximately 0.46% (0.324% per the GitHub Advisory), placing it in the lower percentile for near-term exploitation likelihood. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

1. Identify target: Locate an internet-facing Rekor instance running version >= 0.3.0 and < 1.5.2 using network scanning tools (e.g., Shodan, Censys) or by querying known public Rekor endpoints.
2. Craft decompression bomb: Create a malicious APK file whose gzip-compressed signature or control member expands at approximately a 1000:1 ratio upon decompression (e.g., compress ~2 MB of zero bytes to produce a ~2 GB decompressed payload).
3. Package as Alpine ProposedEntry: Construct a valid JSON request body with the malicious APK content base64-encoded in the spec.package.content field of an Alpine-type ProposedEntry.
4. Submit to unauthenticated endpoint: Send an HTTP POST request to either POST /api/v1/log/entries (createLogEntry) or POST /api/v1/log/entries/retrieve (searchLogQuery) with the crafted payload — no authentication token is required.
5. Trigger OOM crash: The server processes the request through V001Entry.Canonicalize() → fetchExternalEntities() → apk.Unmarshal(packageData), decompressing the full payload into heap memory, exhausting available RAM and causing a fatal Go runtime OOM error or OS OOM-kill that takes the Rekor service offline (GitHub Advisory, Sigstore Advisory).

• Network: Unexpected large HTTP POST requests to /api/v1/log/entries or /api/v1/log/entries/retrieve from unknown or untrusted source IPs; requests with unusually large Content-Length headers or chunked bodies containing Alpine APK content.
• Logs: Rekor server logs showing abrupt process termination or Go runtime fatal error messages (e.g., runtime: out of memory); OS-level OOM-kill events in /var/log/syslog or dmesg referencing the Rekor process (e.g., Out of memory: Kill process <pid> (rekor-server)).
• Process: Sudden disappearance or restart of the rekor-server process; container or pod restarts in Kubernetes environments hosting Rekor with OOMKilled exit status.
• System: Rapid spike in heap memory consumption by the Rekor process immediately preceding a crash, observable via monitoring tools (e.g., Prometheus, cAdvisor) (GitHub Advisory).

Upgrade Rekor to version 1.5.2 or later, which patches the unbounded decompression issue in pkg/types/alpine/apk.go. There is no effective workaround: setting max_request_body_size reduces but does not eliminate exposure because a 1 MB body limit still permits approximately 1 GB of heap allocation at a 1000:1 compression ratio, and adjusting max_apk_metadata_size has no effect since the check is applied after decompression completes. Organizations unable to upgrade immediately should consider restricting network access to Rekor API endpoints at the firewall or load balancer level to trusted sources only (GitHub Advisory, Sigstore Advisory).

The vulnerability was discovered and reported by Hayden-IO and published as a security advisory by the Sigstore/Rekor maintainers on May 26, 2026. Downstream distributions including openSUSE, Amazon Linux 2023, Amazon Linux 2 (Docker), Red Hat, Debian, and Ubuntu have issued their own advisories and package updates in response. No significant public social media discussion or notable independent researcher commentary beyond the official advisory has been identified (Sigstore Advisory).