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MEDIUM 4.7

GHSA-x3g7-qrwc-f6c5

Ember has unneutralized terminal escape/control sequences from Caddy logs injected into the operator's TUI

Quick fix

GHSA-x3g7-qrwc-f6c5 — github.com/alexandre-daubois/ember: upgrade to the fixed version with the command below.

go get github.com/alexandre-daubois/ember@v1.4.2

Details

## Summary

Ember's interactive TUI renders fields taken from the monitored Caddy server's access logs — most notably the request URI — straight to the operator's terminal without neutralising terminal escape or control sequences (CWE-150). Those log fields are populated from arbitrary, unauthenticated HTTP requests, so any remote client can embed ANSI/OSC/CSI control bytes that the operator's terminal emulator interprets when the log row is displayed. The bytes survive the whole pipeline: Caddy escapes them into its JSON access log as unicode escapes, ember's `ParseLogLine` decodes them back to raw `0x1b`/`0x07` bytes, and the row formatters concatenate them into the bubbletea `View()` output with no encoding before they reach `os.Stdout`.

## Impact

An **unauthenticated, remote** attacker who can send HTTP requests to the Caddy server that ember monitors can inject terminal escape sequences into the operator's TUI. The trigger is a single ordinary HTTP request with control bytes in the request target. It requires no authentication; because the payload is reflected through Caddy's normal access log, it works even when ember's log listener is bound only to loopback. When the operator views the Logs tab — ember's default, zero-config mode — the terminal emulator interprets the injected sequences. Broadly-supported, demonstrated impact includes:

- **Monitoring-dashboard spoofing** — CSI cursor/erase/scroll sequences forge or hide log rows so the operator misjudges the monitored server's state. - **Clipboard hijacking (OSC 52)** — attacker-chosen text is written into the operator's system clipboard, staging a payload the operator may later paste into a shell. - **Window-title spoofing (OSC 0/2)** — to support social engineering.

The impact ceiling depends on the operator's terminal emulator and usually requires a further operator action (e.g. a paste) to fully escalate; this is not general-case RCE, though specific terminal emulators have historically escalated escape sequences further. The Certificates and Routes tabs share the same unneutralised render path as secondary sinks. The `--json`/`--once` and daemon (`--expose`) modes are not affected, as they do not render to an interactive terminal.

## References

- https://github.com/alexandre-daubois/ember/blob/main/internal/ui/logtable.go#L18 — the unneutralised render helper (`fitCellLeft`) and row formatters (the sink) - https://github.com/alexandre-daubois/ember/blob/main/internal/fetcher/lognetlistener.go — the unauthenticated TCP access-log listener (input source) - https://github.com/alexandre-daubois/ember/blob/main/internal/fetcher/logentry.go — `ParseLogLine`, where the JSON decode restores raw control bytes - https://cwe.mitre.org/data/definitions/150.html — CWE-150: Improper Neutralization of Escape, Meta, or Control Sequences

Are you affected?

Enter the version of the package you're using.

Affected packages

Go / github.com/alexandre-daubois/ember
Introduced in: 0 Fixed in: 1.4.2
Fix go get github.com/alexandre-daubois/ember@v1.4.2

References