CVE intelligence and bounded remediation

CVE-2023-51451 — Symbolicator is a service used in Sentry

Medium CVSS 4.3

Symbolicator is a service used in Sentry. Starting in Symbolicator version 0.3.3 and prior to version 21.12.1, an attacker could make Symbolicator send GET HTTP requests to arbitrary URLs with internal IP addresses by using an invalid protocol. The responses of those requests could be exposed via Symbolicator's API. In affected Sentry instances, the data could be exposed through the Sentry API and user interface if the attacker has a registered account. The issue has been fixed in Symbolicator release 23.12.1, Sentry self-hosted release 23.12.1, and has already been mitigated on sentry.io on December 18, 2023. If updating is not possible, some other mitigations are available. One may disable JS processing by toggling the option `Allow JavaScript Source Fetching` in `Organization Settings > Security & Privacy` and/or disable all untrusted public repositories under `Project Settings > Debug Files`. Alternatively, if JavaScript and native symbolication are not required, disable Symbolicator completely in `config.yml`.

Severity
Medium
CVSS
4.3 (3.1)
Published
2023-12-22
CISA KEV
Not currently listed
Ecosystem
javascript/npm
Weaknesses
CWE-918

Affected products

  • sentry / symbolicator

Matched remediation archetype

Server-side request forgery and unintended proxying

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Check exposure

  • Inventory server-side URL fetchers, webhooks, importers, previews, redirects, proxies, and protocol handlers reachable from untrusted input.
  • Map egress paths to internal services, metadata endpoints, loopback, private address space, and privileged control planes.
  • Review DNS resolution, redirect, proxy, credential-forwarding, and URL parsing behavior without requesting sensitive targets.

Remediate safely

  • Replace arbitrary destinations with named integrations or a strict allowlist of schemes, hosts, ports, and paths.
  • Resolve and validate every destination and redirect hop, then enforce egress policy independently of application checks.
  • Remove ambient credentials and sensitive headers from fetchers; apply response size, time, and content limits.

Authoritative sources

Complete CVE record and remediation plan

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