Contour: Lua code injection via Cookie Path Rewrite Policy
Contour is a Kubernetes ingress controller using Envoy proxy. From v1.19.0 to before v1.33.4, v1.32.5, and v1.31.6, Contour's Cookie Rewriting feature is vulnerable to Lua code injection. An attacker with RBAC permissions to create or modify HTTPProxy resources can craft a malicious value in spec.routes[].cookieRewritePolicies[].pathRewrite.value or spec.routes[].services[].cookieRewritePolicies[].pathRewrite.value that results in arbitrary code execution in the Envoy proxy. The cookie rewriting feature is internally implemented using Envoy's HTTP Lua filter. User-controlled values are interpolated into Lua source code using Go text/template without sufficient sanitization. The injected code only executes when processing traffic on the attacker's own route, which they already control. However, since Envoy runs as shared infrastructure, the injected code can also read Envoy's xDS client credentials from the filesystem or cause denial of service for other tenants sharing the Envoy instance. This vulnerability is fixed in v1.33.4, v1.32.5, and v1.31.6.
- Published
- Apr 23, 2026
- Updated
- Jul 15, 2026
- EPSS
- 0.8% · 56th percentile
- CWE
- CWE-94
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Report tools
Action score
32
Monitor
Low priority for now.
- CVSS
- 32 / 40 · 8.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.8%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · GitHub_M
- 8.1
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| projectcontour | contour | cpe:2.3:a:projectcontour:contour |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- projectcontour contour1.19.0 and later · before 1.31.6
- projectcontour contour1.32.0 and later · before 1.32.5
- projectcontour contour1.33.0 and later · before 1.33.4
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
projectcontour contour
- >= 1.33.0, < 1.33.4, >= 1.32.0, < 1.32.5, >= 1.19.0, < 1.31.6affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Go | github.com/projectcontour/contour | from 1.19.0 · before 1.31.6 | 1.31.6 |
| Go | github.com/projectcontour/contour | from 1.32.0 · before 1.32.5 | 1.32.5 |
| Go | github.com/projectcontour/contour | from 1.33.0 · before 1.33.4 | 1.33.4 |
Same product
projectcontour: all recordsOther highest-scoring records for the same primary product.
- CVE-2024-36539Insecure permissions in contour v1.28.3 allows attackers to access sensitive data and escalate privileges by obtaining the service account's39Monitor
- CVE-2021-32783Authorization bypass in Contour34Monitor
- CVE-2020-15127Denial of service in Contour30Monitor
- CVE-2026-50149Contour has Improper JWT Verification for Non-SNI Requests on Virtual Hosts with Fallback Certificate Enabled26Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Go:github.com/projectcontour/contour | 1.31.6 | Package registry (OSV) |
| Go:github.com/projectcontour/contour | 1.32.5 | Package registry (OSV) |
| Go:github.com/projectcontour/contour | 1.33.4 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-94 · Improper Control of Generation of Code ('Code Injection')CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- github.com/projectcontour/contour/releases/tag/v1.31.6
- github.com/projectcontour/contour/releases/tag/v1.32.5
- github.com/projectcontour/contour/releases/tag/v1.33.4
- github.com/projectcontour/contour/security/advisories/GHSA-x4mj-7f9g-29h4
- access.redhat.com/security/cve/CVE-2026-41246
- bugzilla.redhat.com/show_bug.cgi?id=2461257
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-41246.json
Vendor advisories and official records. Exploit/PoC links are deliberately left out.