MinIO Signature V4 verification before RELEASE.2026-09-22T19-25-18Z accepts unsigned x-amz- headers, letting a presigned PUT URL be…
Affects MinIO RELEASE.2026-09-21T00-15-41Z and earlier when signed requests leave x-amz-* headers out of SignedHeaders, including presigned PUT URLs for a single object. Fixed in RELEASE.2026-09-22T19-25-18Z.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in RELEASE.2026-09-22T19-25-18Z
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: RELEASE.2026-09-22T19-25-18Z.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 26/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
MinIO Signature V4 verification before RELEASE.2026-09-22T19-25-18Z accepts unsigned x-amz-* headers, letting a presigned PUT URL be escalated into a cross-bucket read.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed, reachable over the network without a login · Unknown: Advisories don't say whether default setups are affected
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.8/10CVSS 8.8
- No patch0/5No signal
What would change the score
- Would score about 71 if added to CISA KEV
- Would score about 66 if CISA's SSVC rates exploitation active
- Would score about 31 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: RELEASE.2026-09-22T19-25-18Z.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- Chainguard MinIO
through RELEASE.2026-09-21T00-15-41Z
Evidence 1
- Advisory
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-122267
Is CVE-2026-122267 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
MinIO's Signature V4 check accepts x-amz-* headers that are not included in the signature. A holder of a presigned PUT URL for one object can use this to copy any object the signing key can read, from any bucket, into that object's name and then read it back, turning a write-only upload grant into a cross-bucket read.Source: github.com
Which versions are affected by CVE-2026-122267?
MinIO: through RELEASE.2026-09-21T00-15-41Z.Source: cve.now feed data
Am I affected, and how do I check?
Versions RELEASE.2026-09-21T00-15-41Z and earlier are in the affected range. The issue applies to presigned PUT URLs for a single object and to Authorization-header requests where x-amz-* headers are omitted from SignedHeaders. Compare the MinIO release string of the running server against this range.Source: github.com
How do I fix CVE-2026-122267?
Upgrade to RELEASE.2026-09-22T19-25-18Z or later, which contains the fix. The sources give no workaround.Source: github.com