fission: Unintended Proxy or Intermediary
CVE-2026-49821 is a high-severity unintended proxy or intermediary vulnerability in fission, with a CVSS 3.1 base score of 7.7 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected fission versions: < 1.24.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.23% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of fission you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N. Scored by CNA (github.com).
Official description
Fission is an open-source, Kubernetes-native serverless framework that simplifies the deployment of functions and applications on Kubernetes. Prior to version 1.24.0, Fission's buildermgr controller processed Package CRDs without verifying that Package.spec.environment.namespace matched Package.metadata.namespace. This issue has been patched in version 1.24.0.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Unintended Proxy or Intermediary
The product receives a request, message, or directive from an upstream component, but the product does not sufficiently preserve the original source of the request before forwarding the request to an external actor that is outside of the product's control sphere.
How developers prevent this class of flaw
- Enforce the use of strong mutual authentication mechanism between the two parties.
- Whenever a product is an intermediary or proxy for transactions between two other components, the proxy core should not drop the identity of the initiator of the transaction. The immutability of the identity of the initiator must be maintained and should be forwarded all the way to the target.
More Unintended Proxy or Intermediary vulnerabilities (CWE-441)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other vulnerabilities in fission
- 8.5 High severity
- 7.7 High severity
- 9.9 Critical severity
- 9.9 Critical severity
- 9.9 Critical severity
- 9.9 Critical severity
Recent Unintended Proxy or Intermediary vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 8.3 High severity
- 10.0 Critical severity
- 9.9 Critical severity
- 9.1 Critical severity
Spotted an error? Tell us.