Security Digest · Vulnerability record
CVE-2026-42354: Sentry's improper authentication on SAML SSO process allows user identity linking
Sentry is an error tracking and performance monitoring tool.
CVSS 9.1 Critical EPSS 0.7% · p54
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.7%, percentile 54: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 54% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
sentry(PyPI) >= 21.12.0, <= 26.4.0, fixed in 26.4.1. Check your lockfile, including transitive dependencies.
What it is
Sentry is an error tracking and performance monitoring tool. From version 21.12.0 to before version 26.4.1, a critical vulnerability was discovered in the SAML SSO implementation of Sentry. The vulnerability allows an attacker to take over any user account by using a malicious SAML Identity Provider and another organization on the same Sentry instance. The victim email address must be known in order to exploit this vulnerability. This issue has been patched in version 26.4.1.
From the GitHub advisory
Impact A critical vulnerability was discovered in the SAML SSO implementation of Sentry. It was reported to us via Sentry's private bug bounty program.
The vulnerability allows an attacker to take over any user account by using a malicious SAML Identity Provider and another organization on the same Sentry instance. The victim email address must be known in order to exploit this vulnerability.
Self-hosted users are only vulnerable if the following conditions are met: - They have more than one organization configured (SENTRYSINGLEORGANIZATION = False). - A malicious user has existing access and permissions to modify SSO settings for another organization in their multi-organization instance.
Patches - Sentry SaaS: The fix was deployed in April. No action is required. - Self-Hosted Sentry: If only a single organization is allowed (SENTRYSINGLEORGANIZATION = True), then no action is needed. Sentry recommends upgrading to version 26.4.1 or higher.
Workarounds User account-based two-factor authentication prevents an attacker from being able to complete authentication with a victim's user account. Organization administrators cannot do this on a user's behalf, this requires individual users to ensure 2FA has been enabled for their account.
Weakness type: CWE-290.
Product: sentry (PyPI) · Assigned by: GitHub_M · Published: 2026-05-08
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| PyPI | sentry | >= 21.12.0, <= 26.4.0 | 26.4.1 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| getsentry | sentry | >= 21.12.0, < 26.4.1 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| GitHub | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.73% probability of exploitation activity in the next 30 days; percentile 54.
Timeline
- — GitHub-reviewed advisory GHSA-rcmw-7mc7-3rj7 published (critical)
- — CVE record published by GitHub_M
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vulnerability records
- GitHub Advisory GHSA-rcmw-7mc7-3rj7 github.com
- CVE.org record CVE-2026-42354 cve.org
- NVD entry CVE-2026-42354 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- github.com github.com
- github.com github.com