EUVD-2026-54156Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
Network-accessible unauthenticated endpoint with no complexity barriers; integrity limited to log forgery and availability limited to pipeline saturation, no confidentiality impact.
Primary rating from Vendor (github).
CVSS VectorVendor: github
Lifecycle Timeline
3DescriptionCVE.org
OpenReception's appointment booking software provides an end-to-end encrypted appointment booking platform. Prior to version 1.0.2, the /api/log endpoint accepts unauthenticated POST requests, applies no schema validation to the message body, writes attacker-controlled content directly into the application's stdout log, interprets newline characters as real line breaks, and enforces no size or rate limits. Three independent abuse modes follow: log injection (forge log lines that look like legitimate system events), log volume DoS (saturate the logging pipeline at sustained 100+ requests per second of small messages), and oversized-payload submission (100 KB payloads accepted; larger sizes not tested). The most operationally damaging mode is log injection. An attacker can inject lines that an operator scanning logs would mistake for real system errors, mask their own activity behind fake noise, or pollute SIEM alerting rules with crafted false positives. A line such as [error]: injected admin error injected from an unauthenticated source is indistinguishable from the application's own error output once written to disk. Version 1.0.2 fixes the issue.
AnalysisAI
Log injection and unauthenticated denial-of-service in OpenReception appointment-booking-software prior to version 1.0.2 expose security operations teams to forged log events indistinguishable from legitimate application output. Any unauthenticated network attacker can POST arbitrary content to the /api/log endpoint, inject newline-delimited fake log lines into stdout and downstream SIEM pipelines, mask malicious activity behind crafted noise, or saturate the logging pipeline at 100+ requests per second. No public exploit has been identified at time of analysis, and the vulnerability is not listed in CISA KEV, but the trivial exploitation bar (no authentication, no special conditions, default configuration) warrants prompt patching.
Technical ContextAI
The vulnerable component is src/routes/api/log/+server.ts in a SvelteKit-based application (EUVD-2026-54156, package appointment-booking-software < 1.0.2). CWE-117 (Improper Output Neutralization for Logs) describes the root cause: attacker-supplied message content is passed directly to the clientLogger family of methods (debug/info/warn/error) without sanitizing newline characters (\n, \r) or control characters, and with no size limit enforced. Because newlines are interpreted as real log-line separators, an attacker can terminate the current log entry and inject arbitrary subsequent lines. The fix introduced in commit 36104d21ee0b6616f1c10273ec9970a27cb56b57 replaces newlines and carriage returns with their escaped string literals, strips ASCII control characters (0x01-0x09, 0x0B, 0x0C, 0x0E-0x1F, 0x7F), and enforces a 4 KB per-message size cap, returning HTTP 400 for oversized payloads.
RemediationAI
Upgrade to appointment-booking-software version 1.0.2, which resolves the issue as confirmed by the GitHub security advisory GHSA-fw48-38r5-7ffj and commit 36104d21ee0b6616f1c10273ec9970a27cb56b57. The fix sanitizes all log message content by escaping newline and carriage return characters, stripping ASCII control characters, and rejecting messages exceeding 4 KB. If an immediate upgrade is not possible, a compensating control is to place a reverse proxy or WAF rule in front of the /api/log endpoint that blocks unauthenticated POST requests or restricts the endpoint to internal/trusted networks only - this eliminates the attack surface entirely but will prevent legitimate client-side logging from functioning. Alternatively, configure network perimeter controls to prevent external access to the application's logging endpoint until the patch can be applied. No workaround addresses the underlying input neutralization flaw without blocking the endpoint.
Same weakness CWE-117 – Improper Output Neutralization for Logs
View allSame technique Code Injection
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External POC / Exploit Code
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