SeaweedFS is a distributed storage system for files and blobs. In versions 4.39 and earlier, the S3 API accepts an external OIDC JWT sent directly in the Authorization header and maps it to an IAM role without enforcing that role's trust policy, so a federated user can assume a role they are not permitted to hold. The standard STS AssumeRoleWithWebIdentity path rejects such a token when the role's trust policy does not trust the token's federated provider, but the direct S3 bearer path validates only the token itself and then authenticates as the mapped role and evaluates that role's attached S3 permissions. As a result, a valid OIDC user whose token would be denied the role through STS can obtain the role's S3 access, including object read, write, and delete, by presenting the raw OIDC JWT directly to the S3 API. This issue is fixed in version 4.40
CVE-2026-77298
This high-severity CVE scores 8.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 79% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 8.7
- EG Score
- 8.7(medium)
- EG Risk
- 39(Track)EG Risk 39/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity87% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 21%
- KEV
- Not listed
Published
August 26, 2026
Last Modified
August 27, 2026
Advisory Details (2)
Auto-updated Aug 26, 2026commit ac524e140a37 (seaweedfs/seaweedfs)
Fix landed in seaweedfs/seaweedfs commit ac524e140a37 — awaiting tagged release
https://github.com/seaweedfs/seaweedfs/commit/ac524e140a37242b2488be9dfffae918da1d4de1S3 OIDC Bearer authentication bypasses IAM role trust policy · Advisory · seaweedfs/seaweedfs · GitHub
https://github.com/seaweedfs/seaweedfs/security/advisories/GHSA-757h-cm9x-wprgWeakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 10× in last 7d / 10× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-08-30 02:43 UTCEG score recompute
- 2026-08-30 01:22 UTCEPSS rescore
- 2026-08-29 03:51 UTCEG score recompute
- 2026-08-28 21:42 UTCEPSS rescore
- 2026-08-27 17:30 UTCEG score recompute
- 2026-08-27 17:07 UTCEG score recompute
- 2026-08-27 14:25 UTCEPSS rescore
- 2026-08-26 22:24 UTCEG score recompute
- 2026-08-26 22:02 UTCEG score recompute
- 2026-08-26 22:01 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Same CWE
10 shownCWE-863
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Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-77298
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