Denial of service via malicious preflight requests in github.com/rs/cors
Priority HIGH 72CWE-770Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 12 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-770.
Summary
Middleware causes a prohibitive amount of heap allocations when processing malicious preflight requests that include a Access-Control-Request-Headers (ACRH) header whose value contains many commas. This behavior can be abused by attackers to produce undue load on the middleware/server as an attempt to cause a denial of service.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00678 52nd percentileScored 2026-11-07
Fix Partial github.com/rs/cors (github.com/rs/cors): 1.11.0github.com/rs/cors (Go): 1.11.0Red Hat: 12 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| github.com/rs/cors | github.com/rs/cors | 1.9.0 to before 1.11.0 | 1.11.0 | Patch available | CNA |
| — | github.com/rs/cors (Go) | 1.9.0 to before 1.11.0 | 1.11.0 | Patch available | GHSA-mh55-gqvf-xfwm |
- github.com/rs/cors Vendorgithub.com/rs/cors Affected 1.9.0 to before 1.11.0 Fixed in 1.11.0 Patch available CNA
- github.com/rs/cors (Go) Vendor— Affected 1.9.0 to before 1.11.0 Fixed in 1.11.0 Patch available GHSA-mh55-gqvf-xfwm
Remediation
- Fix · CNA github.com/rs/cors (github.com/rs/cors) Fixed in 1.11.0
- Fix · GHSA-mh55-gqvf-xfwm github.com/rs/cors (Go) Fixed in 1.11.0 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Multicluster Engine for Kubernetes | Affected | No fix yet: Fix deferred |
| Multicluster Global Hub | Affected | No fix yet: Fix deferred |
| OpenShift Serverless | Affected | No fix yet: Fix deferred |
| Red Hat Advanced Cluster Management for Kubernetes 2 | Affected | No fix yet: Fix deferred |
| Red Hat Ceph Storage 5 | Affected | No fix planned: Out of support scope |
| Red Hat Ceph Storage 6 | Affected | No fix yet: Fix deferred |
| Red Hat Ceph Storage 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift GitOps | Affected | No fix planned: Will not fix |
| Red Hat OpenShift distributed tracing 3 | Affected | No fix yet: Fix deferred |
Not affected: 8 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift AI (RHOAI)
- Red Hat OpenShift Dev Spaces
- Red Hat OpenShift Virtualization 4
- Red Hat OpenShift distributed tracing 3
- Red Hat Trusted Artifact Signer
Timeline
- 2026-10-02 Threatist record created from CVE-2025-47908
- 2026-10-03 Alias added: GHSA-mh55-gqvf-xfwm
- 2026-10-27 EPSS moved to the 50th–90th percentile
References
Sources
- CVE-2025-47908 · CVE Program
- CVE-2025-47908 · NVD
- FIRST EPSS
- GHSA-mh55-gqvf-xfwm · GitHub Advisory Database · CC BY 4.0
- CVE-2025-47908 · Red Hat security data · CC BY 4.0
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