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VulnerabilityPublished

CVE-2026-23742: zalando skipper · Code Injection

Affects zalando skipperSource CVE Database V5

0

Not known to be exploited · CVSS 8.8 High : upgrade to 0.23.0 soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.23.0
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 16 Jan 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade skipper and zalando/skipper to 0.23.0.

Affected software

ProductAffectedFixed in
zalandoskipperAffected
  • <0.23.0
Fixed in
  • 0.23.0
GitHubzalando/skipperpkg:github/zalando/skipperOther threatsAffected
  • <0.23.0
Fixed in
  • 0.23.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

  1. Upgrade all Skipper deployments to version 0.23.0 or later, where the vulnerability is fixed by disabling inline Lua sources by default.
  2. Restrict the ability to create or modify Lua filters to trusted administrators only, especially in Kubernetes Ingress configurations.
  3. Implement strict RBAC policies in Kubernetes to prevent untrusted users from injecting Lua scripts or modifying ingress resources.
  4. Monitor and audit Skipper logs and Kubernetes ingress configurations for unauthorized changes or suspicious Lua filter creation.
  5. Use network segmentation and firewall rules to limit access to Skipper management interfaces.
  6. Employ runtime security tools to detect anomalous Lua script executions or filesystem access patterns by the Skipper process.
  7. Regularly review and rotate secrets accessible to Skipper to minimize exposure in case of compromise.
  8. Conduct penetration testing and vulnerability scanning focused on ingress controllers and reverse proxies to detect similar misconfigurations or vulnerabilities.

Description

CVE-2026-23742 is a high-severity code injection vulnerability in Zalando's Skipper HTTP router and reverse proxy versions prior to 0.23.0. The vulnerability arises from the default configuration allowing inline Lua scripts (-lua-sources=inline,file), which can be exploited if untrusted users can create Lua filters, for example via Kubernetes Ingress resources. Exploitation enables attackers with limited privileges to execute arbitrary Lua code, potentially reading the filesystem accessible to the Skipper process, including sensitive logs and secrets. This can lead to full compromise of confidentiality, integrity, and availability of the affected system. The vulnerability requires at least low privileges (PR:L) but no user interaction and can be exploited remotely over the network. The issue is fixed in version 0.23.0.

References

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