Kyverno before 1.19.2 Denial of Service via Nested Variable Substitution Loop
- 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. A policy has a variable embedded inside a larger string, such as a validation message, rather than the whole value. The attacker-controlled data the variable resolves to re-introduces the same variable template.
- Last modified
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.30% · 22nd 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? →
- 16/100 · 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, a Kubernetes policy engine, is affected by a denial-of-service flaw in its variable substitution logic. An attacker who can reach the cluster over the network and has low-privileged access can create resources with self-referential variable templates, which can hang the admission webhook and block admission cluster-wide.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
Kyverno before 1.19.2 contains a denial of service vulnerability in substituteVariablesIfAny that allows low-privileged users to hang the admission webhook via self-referential variable templates. Attackers can create resources whose annotations re-introduce the embedded policy variable, causing unbounded substitution loops that exhaust CPU and memory and block cluster-wide admission.
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
- Severity8.3/10CVSS 8.3
- No patch0/5No signal
What would change the score
- Would score about 66 if added to CISA KEV
- Would score about 61 if CISA's SSVC rates exploitation active
- Would score about 23 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
A policy has a variable embedded inside a larger string, such as a validation message, rather than the whole value. The attacker-controlled data the variable resolves to re-introduces the same variable template.Upgrade to a fixed version: 1.19.2.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- kyverno kyverno
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-2026-122305
Is CVE-2026-122305 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 Kyverno policy that embeds a variable inside a larger string, such as a validation message, can be made to loop during variable substitution when the data the variable resolves to contains the same variable template again. The loop can deny service to the Kyverno admission webhook, which may block cluster-wide admission and exhaust CPU and memory.Source: github.com, vulncheck.com
Which versions are affected by CVE-2026-122305?
kyverno: before 1.19.2.Source: cve.now feed data
Am I affected, and how do I check?
All Kyverno versions before 1.19.2 are affected, and the bug needs a policy where a variable sits inside a larger string rather than being the whole value. To check a cluster, look at the Kyverno version in use and review policies for variables embedded in longer strings such as validation messages.Source: github.com, vulncheck.com
How do I fix CVE-2026-122305?
Upgrade Kyverno to 1.19.2 or later, which contains the fix.Source: github.com, vulncheck.com