VulnSocial

CVE-2026-33868Disclosure(joinmastodon / mastodon)

LOWCVSS 6.1 · MEDIUM

Signal is active with 1 mentions in latest observed window

Immediate actions

  • Track advisory updates for patch or workaround availability

Recommended action window: Monitor and triage in normal cycle

NVD description

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.8, 4.4.15, and 4.3.21, an unauthenticated Open Redirect vulnerability (CWE-601) exists in the `/web/*` route due to improper handling of URL-encoded path segments. An attacker can craft a specially encoded URL that causes the application to redirect users to an arbitrary external domain, enabling phishing attacks and potential OAuth credential theft. The issue occurs because URL-encoded slashes (`%2F`) bypass Rails path normalization and are interpreted as host-relative redirects. Versions 4.5.8, 4.4.15, and 4.3.21 patch the issue.

joinmastodon CVEsBack to dashboard
0.0/ 10 priority

Sources & remediation

Vendor / third-party advisories
Weakness type (CWE)
CWE-601

Priority

LOW

Exploitation

NONE

PoC

NONE

Patch

NONE

Momentum

STABLE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

  • mastodon

Threat summary

  • 2 mentions across 2 observed days
  • Momentum state: stable

What's happening

  • Technical details provided in 2 signals
  • Disclosure: 2 classified signals
  • Peaked 1d ago at 1 mentions (2026-03-25); latest day: 1
  • 2 total mentions across 2 days

Affected systems

Vendors
joinmastodon
Products
mastodon

Deep dive

Activity timeline2 mentions / 2d
00111Mentions · 2026-03-25: 1Mentions · 2026-03-28: 1Technical Details · 2026-03-25: 1Technical Details · 2026-03-28: 103-2503-28
Signal classification1 categories
Disclosure
2100.0%
Referenced assets2 URLs
Full discourse2 posts
  • pdnuclei-bot@pdnuclei_bot
    Disclosure

    🚨 CVE-2026-33868 - medium 🚨 Mastodon - Open Redirect > Mastodon version < 4.5.8, < 4.4.15, < 4.3.21 is vulnerable to unauthenticated Open Re... 👾 https://cloud.projectdiscovery.io/library/CVE-2026-33868 @pdnuclei #NucleiTemplates #cve

    Post summary

    This tweet announces a medium severity open‑redirect vulnerability (CVE‑2026‑33868) affecting older Mastodon versions, providing a link to a Project Discovery library but no PoC, tool, or patch details.

    00041131
    904 followersView on X
  • CVE@CVEnew
    Disclosure

    CVE-2026-33868 Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.8, 4.4.15, and 4.3.21, an unauthenticated Open Redirect vulnerabilit… https://www.cve.org/CVERecord?id=CVE-2026-33868

    Post summary

    The post only discloses an unauthenticated open‑redirect flaw in earlier Mastodon releases, providing affected versions but no PoC, exploit, or mitigation information.

    00000116
    56.9K followersView on X
CPE platform detail1 entries

1 of 1 entries

PartVendorProductVersionTarget SWTarget HW
Appjoinmastodonmastodon---

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