PatchSiren cyber security CVE debrief
CVE-2026-55629 avwo CVE debrief
CVE-2026-55629 is a vulnerability in Whistle, an HTTP, HTTP2, HTTPS, and WebSocket debugging proxy. The vulnerability allows a remote attacker to read arbitrary files such as /etc/passwd. The issue is reported as fixed in version 2.10.3. Affected deployments should be reviewed for exposure and patched or mitigated. Users should assess their exposure and apply patches or mitigations accordingly. Security teams need to review and verify the vulnerability's impact on their systems.
- Vendor
- avwo
- Product
- whistle
- CVSS
- HIGH 8.7
- CISA KEV
- Not listed in stored evidence
- Original CVE published
- 2026-07-16
- Original CVE updated
- 2026-07-16
- Advisory published
- 2026-07-16
- Advisory updated
- 2026-07-16
Who should care
Users of Whistle HTTP, HTTP2, HTTPS, and WebSocket debugging proxy should apply the patch to prevent arbitrary file reading. Security teams and operators managing Whistle deployments need to review exposure and apply mitigations. This includes assessing the current version of Whistle in use and verifying that it is not exposed to untrusted networks.
Technical summary
Prior to version 2.10.3, lib/service/service.js handles GET /cgi-bin/temp/get by reading req.query.filename, joining it to TEMP_FILES_PATH only when it matches the temporary file pattern, and otherwise passing the user-supplied filename directly to getFile, allowing a remote attacker to read arbitrary files. This issue is specific to Whistle's handling of temporary files and user-supplied input. The vulnerability highlights the importance of secure handling of user-supplied input and temporary files in debugging proxies.
Defensive priority
High
Recommended defensive actions
- Apply the patch to upgrade Whistle to version 2.10.3 or later
- Restrict access to the Whistle debugging proxy
- Monitor Whistle logs for suspicious activity
- Review compensating controls for exposed systems while remediation is scheduled and verified
- Check relevant monitoring, detection, and logs for exposed assets that need extra review
- Track exceptions, retest remediated assets, and close the item only after evidence is documented
- Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
Evidence notes
The CVE record was published on 2026-07-16T20:16:45.577Z and has not been modified since then. The NVD entry is currently 8.7 HIGH. The vulnerability affects Whistle HTTP, HTTP2, HTTPS, and WebSocket debugging proxy. Evidence is limited to CVE and NVD details. The lack of additional sources limits further verification of affected scope and vendor guidance.
Official resources
AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-07-16T20:16:45.577Z and has not been modified since then.