How severe is GHSA-27f5-xjrr-q9ff?

GHSA-27f5-xjrr-q9ff has a CVSS score of 9.6/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by GHSA-27f5-xjrr-q9ff?

GHSA-27f5-xjrr-q9ff affects the following packages: @opensearch-project/opensearch (npm), @opensearch-project/opensearch (npm), @opensearch-project/opensearch (npm), @opensearch-project/opensearch (npm). Ecosystems affected: npm.

How do I fix GHSA-27f5-xjrr-q9ff?

No patched version of @opensearch-project/opensearch has shipped for GHSA-27f5-xjrr-q9ff yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

How do I detect GHSA-27f5-xjrr-q9ff in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @opensearch-project/opensearch, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-27f5-xjrr-q9ff if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is GHSA-27f5-xjrr-q9ff actively exploited in the wild?

No public exploit code has been indexed for GHSA-27f5-xjrr-q9ff yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-27f5-xjrr-q9ff published, and has it been updated?

GHSA-27f5-xjrr-q9ff was published on May 19, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

CRITICAL severity

GHSA-27f5-xjrr-q9ff — @opensearch-project/opens…

CRITICAL

GHSA-27f5-xjrr-q9ff is a critical-severity (CVSS 9.6) vulnerability in @opensearch-project/opensearch. No vendor fix is recorded yet; mitigation options are listed below.

Malware in @opensearch-project/opensearch

Published

May 19, 2026

Updated

Sep 10, 2026

Affected

4 pkgs

Patched

None yet

Exploits

None indexed

Exploitation data as of Sep 10, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

4 pkgs affected

📦@opensearch-project/opensearch📦@opensearch-project/opensearch📦@opensearch-project/opensearch📦@opensearch-project/opensearch

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

Overview

The OpenSearch Project has sustained a security incident involving an external actor gaining force-push permissions within the project's CI infrastructure to embed malicious packages into four release versions of @opensearch-project/opensearch. Users are instructed to immediately take actions recommended in the Remediation section of this advisory.

Affected Versions

Package: @opensearch-project/opensearch

Version	Published (UTC)	Published (America/New_York)
3.5.3	2026-05-12T00:47:39Z	May 11, 2026, 8:47:39 PM EDT
3.6.2	2026-05-12T00:29:34Z	May 11, 2026, 8:29:34 PM EDT
3.7.0	2026-05-12T00:42:29Z	May 11, 2026, 8:42:29 PM EDT
3.8.0	2026-05-12T00:43:54Z	May 11, 2026, 8:43:54 PM EDT

Remediation

Any computer that has these package versions installed or updated between 00:00 UTC 12 May 2026 (8:00 PM EDT 11 May 2026) and 10:00 UTC 12 May 2026 (6:00 AM EDT 12 May 2026) should be considered fully compromised. Steps should immediately be taken to prevent further compromise.

All secrets and keys stored on that computer should be rotated immediately from an alternate system.
The affected packages should be removed immediately, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

References

GHSA-g7cv-rxg3-hmpx https://github.com/TanStack/router/issues/7383

Affected Packages

4 total

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@opensearch-project/opensearch`	all versions	No fix
📦npm	`@opensearch-project/opensearch`	all versions	No fix
📦npm	`@opensearch-project/opensearch`	all versions	No fix
📦npm	`@opensearch-project/opensearch`	all versions	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @opensearch-project/opensearch, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of @opensearch-project/opensearch has shipped for GHSA-27f5-xjrr-q9ff yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

## Overview The OpenSearch Project has sustained a security incident involving an external actor gaining force-push permissions within the project's CI infrastructure to embed malicious packages into four release versions of `@opensearch-project/opensearch`. Users are instructed to immediately take actions recommended in the **Remediation** section of this advisory. ## Affected Versions **Package**: `@opensearch-project/opensearch` | Version | Published (UTC) | Published (America/New_York) | |---------|----------------|------------------------------| | 3.5.3 | 2026-05-12T00:47:39Z | May 11

O3 Security · Impact-Aware SCA

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