CVE-2026-48702 — rekor
HIGHCVE-2026-48702 is a high-severity (CVSS 7.5) CWE-770 vulnerability in github.com/sigstore/rekor. A fix is available for github.com/sigstore/rekor — see the affected versions and patch details below.
Rekor has an OOM Condition due to Unbounded gzip Decompression in Alpine APK Parsing Logic
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-48702.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-48702 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 376,715 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/sigstore/rekorReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Rekor is a software supply chain transparency log. Starting in version 0.3.0 and prior to version 1.5.2, the Package.Unmarshal() function in pkg/types/alpine/apk.go decompresses the signature and control gzip members of an APK file into in-memory buffers without bounding the total decompressed size. The existing max_apk_metadata_size check (default 1MB) is only applied to individual tar entry header sizes after decompression completes, so it does not prevent a decompression bomb from consuming unbounded heap memory. An attacker can craft a gzip stream that compresses at a ~1000:1 ratio (e.g., 2MB compressed zeros → 2GB decompressed). When submitted as spec.package.content in an Alpine ProposedEntry, the server decompresses the full payload into memory during request processing, triggering a fatal Go runtime out-of-memory error or OS OOM-kill that cannot be caught by the server's recover() middleware. This is reachable via two unauthenticated endpoints, POST /api/v1/log/entries (createLogEntry) and POST /api/v1/log/entries/retrieve (searchLogQuery). Both invoke V001Entry.Canonicalize() → fetchExternalEntities() → apk.Unmarshal(packageData), which performs the unbounded decompression. Version 1.5.2 patches the issue. 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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/sigstore/rekor | ≥ 0.3.0&&< 1.5.2 | 1.5.2go get github.com/sigstore/rekor@v1.5.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/sigstore/rekor, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/sigstore/rekor to 1.5.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48702 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-48702 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-48702. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
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…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Hardened Images | cosign-main-3.1.1-0.1.hum1 | RHSA-2026:25138 |
| Red Hat Hardened Images | trivy-main-0.72.0-0.1.hum1 | RHSA-2026:35111 |
| Red Hat Trusted Artifact Signer 1.3 | rhtas/rekor-server-rhel9:1787305397 | RHSA-2026:59439 |
| Red Hat Trusted Artifact Signer 1.4 | rhtas/rekor-server-rhel9:1785391524 | RHSA-2026:50873 |
Frequently Asked Questions
Is CVE-2026-48702 in your dependencies?
O3 Security finds CVE-2026-48702 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.