Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS
CVE-2026-122305 Overview
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.
Critical Impact
Affected Products
- Kyverno: see the vendor advisory for the exact affected versions
Discovery Timeline
- 2026-11-05: CVE-2026-122305 published to the National Vulnerability Database by disclosure@vulncheck.com
- 2026-11-05: last updated in the NVD database
Technical Details for CVE-2026-122305
Vulnerability Analysis
CVE-2026-122305 is a Security Vulnerability weakness (CWE-835) in Kyverno. Based on its CVSS vector, the flaw can be reached over the network, needs some level of access, and needs no user interaction.
With a CVSS base score of 8.3, apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Root Cause
The vendor description states: 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.
Attack Vector
Based on the CVSS vector, the flaw can be reached over the network, needs some level of access, and needs no user interaction. Attack complexity is low complexity.
No exploitation in the wild is confirmed by CISA at the time of the last update. Check the references below for any vendor or researcher proof of concept.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Detection Methods for CVE-2026-122305
Detection Strategies
- Inventory every instance of Kyverno and compare the running version with the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Run an authenticated vulnerability scan once your scanner ships a check for this CVE.
Monitoring Recommendations
- Forward Kyverno application, access and audit logs to your SIEM for retrospective hunting.
- Alert on new processes, configuration changes or outbound connections from the affected service.
- Track the vendor advisory and the CISA KEV catalog for changes in exploitation status.
How to Mitigate CVE-2026-122305
Immediate Actions Required
- Apply the fixed version of Kyverno named in the vendor advisory.
- Prioritize internet facing and business critical instances first.
- Rescan after the change to confirm the exposure is closed.
Patch Information
Use the fixed version listed in the vendor advisory for Kyverno.
Workarounds
- If patching must wait, restrict network access to the affected service and place it behind authentication or a web application firewall rule.
CWE References
Technical References
This entry is built directly from NVD, CISA KEV and EPSS data. Verify fixed versions in the vendor advisory before you deploy.
Frequently asked questions
Related CVEs
Marked is a markdown parser and compiler. From 18.0.0 to 18.0.1, a critical Denial of Service (DoS) vulnerability exists in marked. By providing a specific 3-byte input sequence a tab, a vertical tab, and a newline (\x09\x0b\n)—an unauthenticated attacker can trigger an infinite recursion loop during parsing. This leads to unbounded memory allocation, causing the host Node.js application to crash via Memory Exhaustion (OOM). This vulnerability is fixed in 18.0.2.
Immutable.js provides many Persistent Immutable data structures. Prior to 4.3.9 and 5.1.8, List#set, List#setSize, List#setIn, List#updateIn, and the functional set, setIn, and updateIn mishandle an index or size in the range 2 ** 30 to 2 ** 31 in setListBounds in src/List.js, causing an empty List to enter an uncatchable infinite loop, a populated List to allocate without bound until process abort, or setSize to silently wrap large values. This issue is fixed in versions 4.3.9 and 5.1.8.
Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in mtrudel bandit allows unauthenticated remote denial of service via worker process exhaustion. 'Elixir.Bandit.HTTP1.Socket':do_read_chunked_data!/5 in lib/bandit/http1/socket.ex terminates only when the last-chunk line 0\r\n is followed immediately by the empty trailer line \r\n. RFC 9112 §7.1.2 permits zero or more trailer fields between them. When trailers are present, none of the match clauses fit: the catch-all arm computes a negative to_read, calls read_available!/2, receives <<>> on timeout, and tail-recurses with unchanged state. The worker process is pinned for the lifetime of the TCP connection. A handful of concurrent connections sending RFC-conformant chunked requests with trailer fields is sufficient to exhaust the Bandit worker pool and render the server unresponsive to all further traffic. No authentication, special headers, or large payload is required. Proxies such as NGINX and HAProxy legitimately forward trailer-bearing requests, so servers behind such proxies may be affected without any malicious client involvement. This issue affects bandit: from 1.6.1 before 1.11.1.
Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in benoitc hackney allows Excessive Allocation. The Alt-Svc response header parser in src/hackney_altsvc.erl does not guarantee forward progress. When parse_token/2 receives a non-token, non-whitespace, non-comma byte (e.g. !, @, =, ;), it returns the input unchanged. skip_comma/1 also returns the buffer unchanged when the first byte is not a comma. parse_entries/2 then recurses with identical data, creating a tight infinite tail-recursive loop that pins a scheduler at 100% CPU. The calling process never returns. The entry point parse_and_cache/3 is called synchronously in the connection process on every HTTP response. A single-byte Alt-Svc: ! response header is sufficient to trigger the hang; the header is fully controlled by any HTTP origin the client connects to. This issue affects hackney: from 2.0.0-beta.1 before 4.0.1.
node-tar is a tar archive manipulation library for Node.js. Prior to 7.5.18, tar.replace accepts a checksum-valid tar header with a negative base-256 encoded entry size, causing the archive scanner to make no progress while repeatedly parsing the same header. This issue is fixed in version 7.5.18.
pypdf is a free and open-source pure-python PDF library. Prior to 6.14.2, an attacker can craft a PDF with a page content stream containing a not terminated inline image that uses the ASCII85 or ASCIIHex filters, causing an infinite loop during parsing such as when extracting page text. This issue is fixed in version 6.14.2.
Earn your free CTEM certification.
Learn to scope, prioritize, validate and mobilize fixes for CVEs like CVE-2026-122305 with a free CTEM certification.
Beginner / Practitioner / Program Leader
Explore certifications