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CVE-2026-49294 valhalla CVE debrief

CVE-2026-49294 is a reflected cross-site scripting (XSS) vulnerability in Valhalla, an open-source routing engine and accompanying libraries for use with OpenStreetMap data. The vulnerability affects versions 3.6.3 and prior. The issue arises from improper neutralization of input in the JSONP callback parameter. When a request specifies a JSONP callback, the value is reflected directly into the HTTP response body with Content-Type: application/javascript, without any validation, output encoding, or allowlist filtering. An attacker can craft a URL containing arbitrary JavaScript in the callback parameter; if a victim is induced to load that URL via a <script src='...'> tag, the injected script executes in the context of the serving origin, potentially leading to session token theft, credential disclosure, or actions performed on behalf of the victim.

Vendor
valhalla
Product
Unknown
CVSS
MEDIUM 6.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-15
Original CVE updated
2026-06-16
Advisory published
2026-06-15
Advisory updated
2026-06-16

Who should care

Users of Valhalla versions 3.6.3 and prior should be aware of this vulnerability and take necessary precautions to mitigate the risk.

Technical summary

The vulnerability has a CVSS score of 6.1 and a severity rating of MEDIUM. The CVSS vector is CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N. The weakness is classified as CWE-79.

Defensive priority

MEDIUM

Recommended defensive actions

  • Update to a version of Valhalla that is not vulnerable.
  • Use a Content Security Policy (CSP) to define which sources of content are allowed to be executed within a web page.
  • Implement input validation and output encoding for the JSONP callback parameter.

Evidence notes

The CVE record was published on 2026-06-15T18:16:35.460Z and has not been modified since then. The vulnerability was reported via a security advisory on GitHub.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-49294 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-49294

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-49294 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-49294

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.