Is CVE-2026-49991 in the CISA KEV catalog?

No. CVE-2026-49991 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-49991?

CVE-2026-49991 has a CVSS v3 base score of 8.6 (HIGH).

What is the EPSS score for CVE-2026-49991?

CVE-2026-49991 has an EPSS score of 0.27% (19th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-49991

HIGH

8.6

CVSS v3

NVD

Description

RustFS is a distributed object storage system built in Rust. In 1.0.0-beta.4, authenticated users with only PutObject permission on their own bucket can exploit a path traversal vulnerability in the Snowball auto-extract feature to write arbitrary objects into other users' buckets, completely breaking multi-tenant isolation. The vulnerability chains three flaws: No ../ sanitization in tar entry key normalization; IAM wildcard matching uses raw (uncleaned) paths; and Filesystem path cleaning resolves ../ across bucket boundaries.

CWE-22Path Traversal CWE-862Missing Authorization

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeChanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

Exploit Intelligence

0.27%probability of exploitation in 30 days

19thpercentile

Low risk: more likely to be exploited than 19% of all known CVEs.

References

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

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-26.