---
title: "CVE-2026-42354: Sentry's improper authentication on SAML SSO process allows user identity linking"
url: https://erroneo.us/security/cve/CVE-2026-42354/
description: "CVE-2026-42354 (sentry (PyPI)): Sentry is an error tracking and performance monitoring tool. From version 21.12.0 to before version 26.4.1, a critical…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-05-08
date_modified: 2026-05-13
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-42354"
kev: false
cvss: 9.1
epss: 0.00729
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-42354: Sentry's improper authentication on SAML SSO process allows user identity linking

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- 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.

## Affected packages

- PyPI `sentry` >= 21.12.0, <= 26.4.0 → fixed: 26.4.1

## Affected products (CVE record)

- getsentry sentry: >= 21.12.0, < 26.4.1

## Severity

- GitHub_M CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`
- GitHub CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`

## Exploitation

- 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.

## Sources

- [GitHub Advisory GHSA-rcmw-7mc7-3rj7](https://github.com/advisories/GHSA-rcmw-7mc7-3rj7)
- [CVE.org record CVE-2026-42354](https://www.cve.org/CVERecord?id=CVE-2026-42354)
- [NVD entry CVE-2026-42354](https://nvd.nist.gov/vuln/detail/CVE-2026-42354)
- [github.com](https://github.com/getsentry/sentry/security/advisories/GHSA-rcmw-7mc7-3rj7)
- [github.com](https://github.com/getsentry/sentry/pull/113720)
- [github.com](https://github.com/getsentry/sentry/commit/0c67558ae7fe08738912d4c5233b53ead048da3b)
- [github.com](https://github.com/getsentry/sentry/releases/tag/26.4.1)

---
Source page: https://erroneo.us/security/cve/CVE-2026-42354/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt