Sentry EUVD-2026-101578

Exploitation requires that the target Sentry instance has SAML SSO configured and enabled (versions 26.5.0 up to but not including 26.7.2). The attacker must control a SAML identity provider and must socially engineer an already-authenticated Sentry user into opening a crafted malicious URL (required user interaction). A critical limiting precondition is the victim's browser cookie behavior: the attack only succeeds if the browser accepts the cross-site cookie context - specifically Firefox sending SameSite=None cookies, or Chromium with third-party cookies explicitly enabled - which is not the default in current Chromium builds, substantially narrowing the exploitable population. Sentry SaaS was remediated on July 27, 2026, so SaaS tenants are not affected; the condition applies to self-hosted deployments on vulnerable versions.

The CVSS 4.0 base score of 7.6 (High) is driven by VC:H/VI:H - full account takeover compromises both confidentiality and integrity of the victim's Sentry account - with AV:N (a malicious URL delivered over the network). However, two metrics materially temper real-world risk: AT:P (a specific attack requirement) and UI:P (victim interaction required). The attack requirement is concrete and limiting - the victim's browser must accept a cross-site cookie context (Firefox with SameSite=None, or Chromium with third-party cookies explicitly enabled), a configuration that modern Chromium increasingly blocks by default, so a large share of potential victims are not exploitable out of the box. PR:N indicates no attacker privileges on Sentry, but the attacker must separately control a SAML identity provider and must socially engineer an already-authenticated user, which is a non-trivial precondition. EPSS, SSVC, and POC signals are ALL ABSENT from the input, and KEV status is not listed (no active-exploitation signal). This is therefore a genuine priority specifically for organizations running SAML SSO on self-hosted Sentry versions 26.5.0 through pre-26.7.2, but it is not a mass/wormable issue: exploitation is targeted, interaction-gated, and dependent on victim browser configuration rather than opportunistic. No conflicting signals were found between the CVSS vector and the description - both agree on network delivery with required user interaction and an environmental browser precondition.

An attacker who operates a SAML identity provider crafts a malicious link and, through phishing, convinces an authenticated Sentry user to open it in a browser that accepts cross-site cookies (e.g. Firefox with SameSite=None or Chromium with third-party cookies enabled). The SAML SSO identity-linking flow then binds the attacker's IdP identity to the victim's Sentry account, giving the attacker control of that account. No public proof-of-concept exploit code was identified in the provided data.