Applications and libraries which misuse connection.serverAuthenticate (via callback field ServerConfig.PublicKeyCallback) may be susceptible to an authorization bypass. The documentation for ServerConfig.PublicKeyCallback says that "A call to this function does not guarantee that the key offered is in fact used to authenticate." Specifically, the SSH protocol allows clients to inquire about whether a public key is acceptable before proving control of the corresponding private key. PublicKeyCallback may be called with multiple keys, and the order in which the keys were provided cannot be used to infer which key the client successfully authenticated with, if any. Some applications, which store the key(s) passed to PublicKeyCallback (or derived information) and make security relevant determinations based on it once the connection is established, may make incorrect assumptions. For example, an attacker may send public keys A and B, and then authenticate with A. PublicKeyCallback would be called only twice, first with A and then with B. A vulnerable application may then make authorization decisions based on key B for which the attacker does not actually control the private key. Since this API is widely misused, as a partial mitigation golang.org/x/[email protected] enforces the property that, when successfully authenticating via public key, the last key passed to ServerConfig.PublicKeyCallback will be the key used to authenticate the connection. PublicKeyCallback will now be called multiple times with the same key, if necessary. Note that the client may still not control the last key passed to PublicKeyCallback if the connection is then authenticated with a different method, such as PasswordCallback, KeyboardInteractiveCallback, or NoClientAuth. Users should be using the Extensions field of the Permissions return value from the various authentication callbacks to record data associated with the authentication attempt instead of referencing external state. Once the connection is established the state corresponding to the successful authentication attempt can be retrieved via the ServerConn.Permissions field. Note that some third-party libraries misuse the Permissions type by sharing it across authentication attempts; users of third-party libraries should refer to the relevant projects for guidance.
CVSS Details
- CVSS 3.1 Base Score: 9.1
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Alpine Linux | — | Upgrade rclone | Aug 8, 2025 | Dec 11, 2024 |
| Amazon Linux Ami 2 | — | Upgrade amazon-cloudwatch-agentUpgrade nerdctlUpgrade nerdctl-debuginfoUpgrade containerd-stressUpgrade runfinch-finchUpgrade containerdUpgrade containerd-debuginfo | Feb 4, 2025 | Dec 12, 2024 |
| Amazon_linux_2023 | — | Upgrade runfinch-finchUpgrade containerd-stress-debuginfoUpgrade nerdctlUpgrade containerdUpgrade containerd-debugsourceUpgrade containerd-debuginfoUpgrade amazon-cloudwatch-agentUpgrade containerd-stress | Feb 17, 2025 | Dec 11, 2024 |
| Debian | — | No solution exists | May 15, 2025 | Dec 12, 2024 |
| Redhat Openshift | — | Upgrade ose-oauth-proxy-rhel9Upgrade ose-ibmcloud-cluster-api-controllers-rhel9Upgrade ose-ibmcloud-cluster-api-controllers-rhel8 | Aug 10, 2026 | Dec 11, 2024 |
| Splunk | — | Upgrade Splunk Enterprise to version 9.1.10Upgrade Splunk Enterprise to version 9.2.6Upgrade Splunk Enterprise to version 9.4.4Upgrade Splunk Enterprise to version 9.3.6Upgrade Splunk Enterprise to version 10.0.1Upgrade Splunk Enterprise to version 9.1.9Upgrade Splunk Enterprise to version 9.2.7Upgrade Splunk Enterprise to version 9.4.2Upgrade Splunk Enterprise to version 9.3.4Upgrade Splunk Enterprise to version 9.3.5Upgrade Splunk Enterprise to version 9.4.3Upgrade Splunk Universal Forwarder to version 9.4.2Upgrade Splunk Enterprise to version 9.2.8 | Sep 30, 2025 | Dec 11, 2024 |
| Suse | — | Upgrade helm-zsh-completionUpgrade kubevirt-manifestsUpgrade helm-fish-completionUpgrade rime-schema-quickUpgrade rclone-bash-completionUpgrade kubevirt-virt-apiUpgrade minikubeUpgrade trivyUpgrade rime-schema-extraUpgrade rime-schema-double-pinyinUpgrade rime-schema-luna-pinyinUpgrade apptainer-leapUpgrade rime-schema-terra-pinyinUpgrade supportutils-plugin-saltUpgrade rime-schema-defaultUpgrade rime-schema-essay-simpUpgrade docker-machine-driver-kvm2Upgrade cheatUpgrade gitea-tea-zsh-completionUpgrade supportutils-plugin-susemanager-clientUpgrade rcloneUpgrade rime-schema-arrayUpgrade spacecmdUpgrade minikube-bash-completionUpgrade git-bug-fish-completionUpgrade gitea-teaUpgrade apptainer-sle15_5Upgrade kubevirt-virt-controllerUpgrade rime-schema-customUpgrade kubevirt-testsUpgrade rime-schema-stenotypeUpgrade dracut-saltbootUpgrade rime-schema-allUpgrade kubevirt-virt-exportserverUpgrade minikube-zsh-completionUpgrade rime-schema-emojiUpgrade kubevirt-virt-exportproxyUpgrade git-bug-bash-completionUpgrade rime-schema-bopomofoUpgrade git-bugUpgrade rime-schema-wugniuUpgrade govulncheck-vulndbUpgrade rime-schema-cangjieUpgrade google-guest-agentUpgrade rime-schema-combo-pinyinUpgrade helm-bash-completionUpgrade rime-schema-middle-chineseUpgrade rime-schema-essayUpgrade kubevirt-virt-operatorUpgrade kubevirt-container-diskUpgrade rime-schema-wubiUpgrade gitea-tea-bash-completionUpgrade kubevirt-pr-helper-confUpgrade rime-schema-cantoneseUpgrade rime-schema-strokeUpgrade minikube-fish-completionUpgrade rime-schema-ipaUpgrade golang-github-prometheus-promuUpgrade apptainer-sle15_6Upgrade kubevirt-virt-launcherUpgrade rime-schema-pinyin-simpUpgrade helmUpgrade grafanaUpgrade rime-schema-scjUpgrade obs-service-kubevirt_containers_metaUpgrade apptainerUpgrade kubevirt-virtctlUpgrade git-bug-zsh-completionUpgrade rime-schema-soutzoeUpgrade rime-schema-preludeUpgrade rclone-zsh-completionUpgrade kubevirt-virt-handler | Dec 5, 2025 | Jun 18, 2025 |
| Ubuntu | — | Upgrade google-guest-agentUpgrade google-guest-agent (Ubuntu Pro)Upgrade golang-golang-x-crypto-dev (Ubuntu Pro)Upgrade golang-go.crypto-dev (Ubuntu Pro) | Oct 24, 2025 | Dec 12, 2024 |
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