Is CVE-2026-49991 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-49991 being exploited in the wild.

How severe is CVE-2026-49991?

High severity, with a CVSS score of 8.6, published 26 June 2026.

Is there a fix for CVE-2026-49991?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-49991 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-49991?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-49991: RustFS path traversal in Snowball auto-extract feature

CVE-2026-49991 · Severity: high · CVSS 8.6 · Published 2026-06-26

RustFS is a distributed storage system used to manage large amounts of data across multiple users or 'tenants.' A security flaw in its data extraction feature allows a user to bypass security boundaries and write files into other users' private storage areas. This could lead to unauthorized data modification, malware injection, or the corruption of sensitive information belonging to other customers.

Quick answers

Is CVE-2026-49991 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-49991 being exploited in the wild.
How severe is CVE-2026-49991?: High severity, with a CVSS score of 8.6, published 26 June 2026.
Which products and versions are affected?: rustfs RustFS 1.0.0-beta.4.
Is there a fix for CVE-2026-49991?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-49991 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-49991?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A path traversal vulnerability exists in the RustFS Snowball auto-extract feature due to a chain of three flaws. First, the 'normalize_extract_entry_key' function fails to sanitize '../' sequences in tar entry keys. Second, IAM wildcard matching is performed against raw, uncleaned paths, allowing 'attacker-bucket/../victim-bucket' to match 'attacker-bucket/*'. Finally, the filesystem path resolution logic resolves parent directory references across bucket boundaries. An authenticated attacker with PutObject permissions on their own bucket can upload a malicious archive that, when extracted, writes arbitrary files into a victim's bucket. No patch is currently listed in the advisory.

Affected products

rustfs RustFS 1.0.0-beta.4

Timeline

2026-06-01: advisory: GitHub advisory published
2026-06-26: disclosed: NVD publication date

References

https://github.com/rustfs/rustfs/security/advisories/GHSA-f4vq-9ffr-m8m3

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