CVE-2026-15689
CRITICALCVE-2026-15689 is a critical-severity (CVSS 9.8) CWE-640 vulnerability. O3 Security confirms whether CVE-2026-15689 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Dancer2::Plugin::Auth::Extensible versions through 0.713 for Perl allow password reset link poisoning via the request Host header in _default_email_password_reset and _default_welcome_send. Both…
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-15689.
Description
Dancer2::Plugin::Auth::Extensible versions through 0.713 for Perl allow password reset link poisoning via the request Host header in _default_email_password_reset and _default_welcome_send.
Both default emails emit a link of the form $base/login/$code, whose authority comes from the request Host header, or from X-Forwarded-Host under behind_proxy (obtained from Dancer2's request->base function). A POST to /login carrying submit_reset and a username needs no authentication: it stores a fresh reset code against that account and mails the account holder a link to a host of the sender's choosing. The welcome mail takes the same path when the application calls create_user with email_welcome set.
Through 0.711 the handlers read request->uri_base and request->base directly; Versions 0.712 and later provide an uri_base configuration key that defaults to the untrusted request->uri_base when unset.
The default configuration with reset_password_handler enabled and the default message text, a recipient who follows the link hands a working reset code to the sender's host, which is enough to take over the account.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2026-15689 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-15689 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-15689. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-15689 in your dependencies?
O3 detects CVE-2026-15689 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.