Live Exposure Defense: From CVE to Confirmed Exposure in 12 Hours – See more

Back
New CVE Detected

CVE-2026-87816 – View-Limit Bypass via Race Condition – PasswordPusher before 2.11.1

Be the first to know when new zero-days emerge:

Subscribe to Email Alerts
Subscribe to RSS Feed

Summary

CVE-2026-87816 is a time-of-check-to-time-of-use (TOCTOU) race condition in PasswordPusher, an open-source application for sharing sensitive information (e.g., passwords) via self-expiring links. The flaw allows an unauthenticated attacker to bypass a push’s expire_after_views limit by sending concurrent requests, allowing a secret configured for a single view to be retrieved multiple times before the view count is incremented and the push is expired. The issue affects PasswordPusher versions prior to 2.11.1 and is rated High severity.

Technical details

  • Root cause (CWE-362): The show-secret flow in pushes_controller.rb (and the equivalent JSON API controller) checks the view limit, validates expiration, delivers the secret payload, and only afterward logs the view/increments the view count — with no database lock, transaction, or optimistic concurrency control tying these steps together.
  • Trigger conditions: A push is created with a view limit (e.g., expire_after_views: 1, the "one-time secret" mode) and its access URL becomes known to more than one party (e.g., shared in a Slack/Teams/email channel).
  • Attack vector: Network-based, unauthenticated, no user interaction required. An attacker races the legitimate recipient by issuing multiple simultaneous GET requests to the push’s show endpoint (web UI or JSON API) before the view is recorded.
  • Impact: Defeats PasswordPusher’s core security guarantee — secrets intended to self-destruct after a set number of views can instead be viewed by multiple parties, resulting in unauthorized disclosure of confidential information (credentials, tokens, etc.). No integrity or availability impact is associated with this issue.

Affected software

  • PasswordPusher (pglombardo/PasswordPusher) versions prior to 2.11.1
  • Both the web application show action and the JSON API v1 show action are affected

Severity

  • CVSS v4.0: 8.7 (High) — AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
  • CVSS v3.1: 7.5 (High) — AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Mitigation and recommended actions

  • Immediate: Upgrade PasswordPusher to version 2.11.1 or later, which serializes the view-check/log/expire sequence using database-level locking to close the race window.
  • If upgrading immediately is not possible:
    • Treat any secret shared via PasswordPusher instances running an affected version as potentially exposed to more than the intended recipient, especially secrets shared in group channels.
    • Restrict who can access the shared link/channel until the instance is patched, and rotate any credentials pushed through an affected instance where exposure cannot be ruled out.
    • Monitor push view/audit logs for unexpected multiple or near-simultaneous views on secrets configured with a low expire_after_views value.

References

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report

How IONIX’s External Exposure Management Platform Detects and Validates
Zero-Days to Shrink MTTR

1

Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

2

Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

3

Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report
Close

Subscribe to Threat Center RSS

Copy/paste the link below into your preferred RSS reader or follow these instructions to subscribe to Slack alerts.

Open RSS feedSlack setup instructions

Close

Get Real-Time CVE Alerts to Your Email

Be the first to know when new zero-days emerge