Kyverno 1.17.0 before 1.19.2 Cross-Namespace Resource Overwrite via NamespacedMutatingPolicy
Affects Kyverno 1.17.0 up to 1.19.2 when a NamespacedMutatingPolicy has mutateExisting enabled and uses a raw CEL targetMatchConstraints expression. Fixed in Kyverno 1.19.2.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 1.19.2
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. NamespacedMutatingPolicy with evaluation.mutateExisting.enabled=true Kyverno versions 1.17.0 up to (not including) 1.19.2 are affected Policy uses a raw CEL targetMatchConstraints.expression that returns a map literal fabricating the target
- Last modified
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.33% · 26th percentile
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 17/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Kyverno versions from 1.17.0 up to (but not including) the fixed release contain an authorization bypass that lets a namespace tenant overwrite resources in other namespaces, including Secrets, Deployments, and policies. An attacker with low-privilege access can exploit this remotely over the network through a crafted NamespacedMutatingPolicy, because the privileged background controller acts on the fabricated target.
Read the original description
Kyverno from 1.17.0 before 1.19.2 contains an authorization bypass vulnerability that allows namespace tenants to overwrite resources in other namespaces via NamespacedMutatingPolicy mutate-existing targetMatchConstraints.expression. Attackers can return a CEL map literal fabricating a target with an attacker-chosen metadata.namespace, causing the privileged background controller to overwrite Secrets, Deployments, or policies cluster-wide.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Unknown. No tracked technology or package matched
- Severity9.4/10CVSS 9.4
- No patch0/5No signal
What would change the score
- Would score about 67 if added to CISA KEV
- Would score about 62 if CISA's SSVC rates exploitation active
- Would score about 24 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
NamespacedMutatingPolicy with evaluation.mutateExisting.enabled=true Kyverno versions 1.17.0 up to (not including) 1.19.2 are affected Policy uses a raw CEL targetMatchConstraints.expression that returns a map literal fabricating the targetUpgrade to a fixed version: 1.19.2.
Timeline
- CVE published
- First seen by cve.now
- Posted on X by cve.now
Affected versions
- kyverno kyverno
From 1.17.0 · fixed in 1.19.2
Evidence 2
- Advisory
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-122303
Is CVE-2026-122303 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A namespace tenant can overwrite the full content of pre-existing resources in other namespaces, and cluster-scoped resources, using the privileged background controller's rights. In some cases this can lead to code execution as a workload's ServiceAccount.Source: github.com, vulncheck.com
Which versions are affected by CVE-2026-122303?
kyverno: from 1.17.0 before 1.19.2.Source: cve.now feed data
Am I affected, and how do I check?
Kyverno versions 1.17.0 up to, but not including, 1.19.2. The setup involves a NamespacedMutatingPolicy with evaluation.mutateExisting.enabled=true whose targetMatchConstraints.expression is raw CEL returning a map literal. To check, look at the installed Kyverno version and search policies for mutateExisting and raw CEL targetMatchConstraints expressions.Source: github.com, vulncheck.com
How do I fix CVE-2026-122303?
Upgrade Kyverno to 1.19.2 or later, which is the listed fixed version.Source: github.com, vulncheck.com