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CVE-2026-42504VulnerabilityPublished

Red Hat Security Advisory: osbuild-composer security update

Affects Red Hat osbuild-composerSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2026-42504· High 7.5

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 29 Oct 2026, 17:07 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CISA-ADPCVSS 3.17.5
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:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 2 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
Go standard librarymimeAffected
  • >=1.26.0-0 <1.26.4
Fixed in
  • 1.26.4
Go standard librarymimeAffected
  • <1.25.11
Fixed in
  • 1.25.11
Gomimepkg:golang/mimeOther threatsAffected
  • <1.25.11
  • >=1.26.0-0 <1.26.4
Fixed in
  • 1.25.11
  • 1.26.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Red Hat has released updated osbuild-composer packages for Red Hat Enterprise Linux 9.2 and related variants that fix these vulnerabilities. Users should apply the provided security update promptly to remediate the issues. For detailed instructions on applying the update, refer to the Red Hat advisory at https://access.redhat.com/articles/11258. No additional mitigation steps are indicated beyond applying the official update.

Description

Red Hat has issued a security update for osbuild-composer, a service used to build customized OS artifacts such as VM images and OSTree commits. The update addresses multiple denial of service vulnerabilities and a man-in-the-middle vulnerability in various Golang components used by osbuild-composer. These vulnerabilities include issues in MIME header parsing, gRPC request handling, HTTP Range header processing, TLS extension handling, multipart form parsing, HTTP/2 SETTINGS frame processing, and certificate validation. The update is rated as important by Red Hat and applies to Red Hat Enterprise Linux 9.2 and related variants.

References

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