Red Hat Security Advisory: osbuild-composer security update
Affects Red Hat osbuild-composerSource GCVE Database
Mentioned vulnerabilities
Not known to be exploited · CVSS 7.5 High : upgrade Red Hat mime to 1.26.4 or 1.25.11 soon.
Data as of 30 Oct 2026, 02:31 UTC
Thin evidence
One scorer or none| CISA-ADP | CVSS 3.1 | 7.5 |
|---|
- Patch
- Available – fixed in 1.26.4, 1.25.11
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 2 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade mime to 1.26.4 or 1.25.11.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Go standard librarymime | Affected
| Fixed in
|
| Go standard librarymime | Affected
| Fixed in
|
Gomimepkg:golang/mimeOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
A service for building customized OS artifacts, such as VM images and OSTree commits, that uses osbuild under the hood. Besides building images for local usage, it can also upload images directly to cloud. It is compatible with composer-cli and cockpit-composer clients. Security Fix(es): * mime: golang: Golang MIME: Denial of Service via maliciously-crafted MIME header (CVE-2026-42504) * google.golang.org/grpc: gRPC-Go: Denial of Service via malformed RPC requests (CVE-2026-84445) * net/http: golang: golang: Denial of Service via crafted HTTP Range headers (CVE-2026-78667) * crypto/tls: golang: crypto/tls: Denial of Service via multiple ECH outer extension references (CVE-2026-97031) * net/textproto: mime/multipart: golang: golang: Denial of Service via memory limit bypass in multipart form parsing (CVE-2026-94440) * net/http: net/http/internal/http2: golang.org/x/net/http2: net/http: Denial of Service via excessive HTTP/2 SETTINGS frames (CVE-2026-78669) * crypto/x509: golang: crypto/x509: Man-in-the-middle attacks via untrusted intermediate certificates (CVE-2026-111943) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
References
- access.redhat.com/errata/RHSA-2026:91587 (opens in a new tab)
- access.redhat.com/security/updates/classification/ (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2484204 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2533175 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2548334 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2548336 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2548341 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2548344 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2556068 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_91587.json (opens in a new tab)