SUSE Rancher Manager meta proxy missing filtering discloses Rancher credentials to cloud providers

CVE-2026-88811 is a missing filtering flaw in the SUSE Rancher Manager meta proxy, the component the Rancher UI uses to query cloud provider APIs on behalf of a user during cluster or node provisioning. When the proxy forwards a request to a configured third-party host, it does not reliably strip the caller’s own Rancher credentials from the outgoing request. The result is that Rancher session cookies, API tokens, or other credentials supplied in the request can be transmitted to the cloud provider alongside the intended API call. Affected versions per the official record are SUSE Rancher 2.15.0 through 2.15.2, 2.14.0 through 2.14.6, and 2.13.0 through 2.13.10; the GitHub security advisory also lists 2.12.0–2.12.14 and 2.11.0–2.11.18. Fixed releases are 2.15.3, 2.14.7, 2.13.11, plus 2.12.15 and 2.11.19.

The vendor rates this CRITICAL 9.1 using CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. That severity is directionally correct because Rancher Manager is a Kubernetes fleet control plane: a leaked admin token can become fleet-scale cluster and cloud account compromise. However, the PR:N component is optimistic. The leaked credentials belong to a signed-in Rancher user, so an attacker either needs an existing low-privilege session or must control or compromise the third-party cloud provider host. No active exploitation or public PoC exists yet, but the high-value deployment role keeps this at CRITICAL rather than HIGH.

Sources.

1. NVD — CVE-2026-88811
2. GitHub Security Advisory — Rancher credentials disclosed to third-party hosts by the Rancher Manager meta proxy
3. Rapid7 vulnerability database — CVE-2026-88811
4. Tenable — CVE-2026-88811
5. VulDB — CVE-2026-88811
6. Launchpad Bugs — CVE-2026-88811
7. CCN-CERT vulnerability bulletin — CVE-2026-88811
8. Mallory — Credential Disclosure in SUSE Rancher Manager Meta Proxy

Run on a jump host with kubectl access to the Rancher management cluster, or from the Rancher server console. Example: bash check_cve-2026-88811.sh https://rancher.example.com <RANCHER_TOKEN>. If the optional token is omitted, the script will attempt kubectl -n cattle-system to fetch the Rancher deployment image tag. Cluster-admin privileges are needed only for the kubectl path; the API token path uses the supplied Rancher token.

#!/bin/bash
# CVE-2026-88811 SUSE Rancher Manager meta proxy credential leak check
# Usage: ./check_cve-2026-88811.sh [RANCHER_URL] [RANCHER_TOKEN]
# Exit codes: 0=VULNERABLE, 1=PATCHED, 2=UNKNOWN
set -u

RANCHER_URL="${1:-}"
TOKEN="${2:-}"
VERSION=""

if [ -n "$TOKEN" ] && [ -n "$RANCHER_URL" ]; then
  resp=$(curl -sk -m 15 -H "Authorization: Bearer $TOKEN" "$RANCHER_URL/v3/settings/server-version" 2>/dev/null || true)
  VERSION=$(echo "$resp" | sed -n 's/.*"value":"\([^"]*\)".*/\1/p' | head -1)
elif command -v kubectl >/dev/null 2>&1; then
  img=$(kubectl -n cattle-system get deployment rancher -o jsonpath='{.spec.template.spec.containers[0].image}' 2>/dev/null || true)
  VERSION="${img##*:}"
fi

if [ -z "$VERSION" ]; then
  echo UNKNOWN
  exit 2
fi

VERSION="${VERSION#v}"
vuln=0

if [[ "$VERSION" =~ ^([0-9]+)\.([0-9]+)\.([0-9]+) ]]; then
  major="${BASH_REMATCH[1]}"
  minor="${BASH_REMATCH[2]}"
  patch="${BASH_REMATCH[3]}"

  if { [ "$major" -eq 2 ] && [ "$minor" -eq 11 ] && [ "$patch" -lt 19 ]; } || \
     { [ "$major" -eq 2 ] && [ "$minor" -eq 12 ] && [ "$patch" -lt 15 ]; } || \
     { [ "$major" -eq 2 ] && [ "$minor" -eq 13 ] && [ "$patch" -lt 11 ]; } || \
     { [ "$major" -eq 2 ] && [ "$minor" -eq 14 ] && [ "$patch" -lt 7 ]; } || \
     { [ "$major" -eq 2 ] && [ "$minor" -eq 15 ] && [ "$patch" -lt 3 ]; }; then
    vuln=1
  fi
fi

if [ "$vuln" -eq 1 ]; then
  echo VULNERABLE
  exit 0
else
  echo PATCHED
  exit 1
fi