CVE-2026-97731
CVE-2026-97731 — MinIO through 7aac2a2 does not verify that every x-amz-* header present on a request also appears in the client-supplied…
MinIO through 7aac2a2 does not verify that every x-amz-* header present on a request also appears in the client-supplied X-Amz-SignedHeaders list. extractSignedHeaders() in cmd/signature-v4-utils.go iterates only the claimed list and never enumerates the headers that actually arrived, and thus a header that arrives unsigned is neither hashed into the canonical request nor rejected. Because cmd/api-router.go dispatches CopyObject on the presence of x-amz-copy-source alone, the holder of a presigned PUT URL scoped to a single object can add that header to the unmodified URL and cause a server-side copy, executed as the signer, of any object the signing key can read. A grant to write one object becomes a read of every bucket that key can reach. Amazon S3 rejects the equivalent request with HTTP 403 AccessDenied. The minio/minio GitHub repository was archived in April 2026; pgsty/silo before 1233254 is also affected.
Published Updated Sources: MinIO (CNA), GitHub, GitHub Security Advisory
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.
Exploitation
Exploit code
public exploit, none observed
EPSS
Not scored
FIRST has not published a score
CVSS base
7.1
high
Remediation
The vendor's own words where we have them.
Upgrade MinIO to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.
First 24 hours
Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.
- Identify exposed assets running affected vendor/product/version combinations.
- Prioritize based on EPSS, PoC availability, and external exposure.
- Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.
Affected scope
Vendor, product and version as the advisories word them.
| Vendor | Product | Versions | Status |
|---|---|---|---|
| MinIO | MinIO | 0 to <= 7aac2a2c5b7c882e68c1ce017d8256be2feea27f | Vulnerable |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Availability
None
Confidentiality
High
Integrity
Low
Scope
Unchanged
Attack Complexity
Low
Attack Vector
Network
Privileges Req
Low
User Interaction
None
Every base score collected
Sources score independently and disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Source |
|---|---|---|---|---|---|
| 7.1 | CVSS 3.1 | high | — | — | MinIO (CNA), GHSA |
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Weakness & attack patterns
- CWE-347
Public exploit
Capability, not use: code existing is a different claim from anyone running it.
Repositories
1
Detection
Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.
- Search application, proxy, and WAF logs for requests touching /signature-v4-utils.go, /api-router.go, /minio, /silo.
- Prioritize edge telemetry for network-reachable MinIO.
- Monitor for scanner or exploit-pattern traffic after 1 public PoC repositories were reported.
Timeline
What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.
- 2026
Added · CVSS 3.1 7.1 (AV:N)
Sep 25, 2026 · NVD
Initial · CVE published
Sep 25, 2026 · NVD
Added · GHSA-r7wh-x6rf-8g63 published (high)
Sep 25, 2026 · GitHub Security Advisory
References
4 on the record
- silo.pgsty.com/about/security-advisories/#sn-2026-011
Vendor Advisory
- github.com/pgsty/silo/commit/1233254309b15571f101b2b26d531951ceaeef1e
Exploit, Third Party Advisory
- nvd.nist.gov/vuln/detail/CVE-2026-97731
NVD
- github.com/advisories/GHSA-r7wh-x6rf-8g63
Exploit, Third Party Advisory
Elsewhere on this site
- MinIOevery CVE for this vendor
- Unclassifiedsame class
- CWE-347other pages naming this weakness
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record1
What should defenders know first?
CVE-2026-97731 is MinIO through 7aac2a2 does not verify that every x-amz-* header present on a request also appears in the client-supplied…, a high vulnerability affecting MinIO from MinIO. The current evidence does not list it in CISA KEV, and the exploit status is: Active exploitation is not confirmed from current sources for CVE-2026-97731. Public exploit evidence is: 1 public PoC repositories reported; 0 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 7.1 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.