CVE-2025-0239: Alt-Svc ALPN validation failure when redirected

Published Jan 7, 2025
·
Updated

When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6.

Other sources

When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site. This vulnerability affects Firefox < 134 and Firefox ESR < 128.6.

— Red Hat

When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site. This vulnerability affects Firefox < 134, Firefox ESR < 128.6, Thunderbird < 134, and Thunderbird < 128.6.

— OSV

Affected Software

22 affected componentsFixes available
Mozilla Thunderbird<134
134
Mozilla Firefox ESR<128.6
128.6
Mozilla Firefox<128.6.0
Mozilla Firefox<134.0
Mozilla Thunderbird<128.6.0
Mozilla Thunderbird>=129.0<134.0
ubuntu/mozjs52*
ubuntu/mozjs38*
ubuntu/firefox<134.0+build1-0ubuntu0.20.04.1
134.0+build1-0ubuntu0.20.04.1
ubuntu/mozjs68*
ubuntu/mozjs52*
ubuntu/mozjs102*
ubuntu/mozjs78*
ubuntu/mozjs91*
ubuntu/thunderbird<1:140.7.1+build1-0ubuntu0.22.04.1
1:140.7.1+build1-0ubuntu0.22.04.1
ubuntu/mozjs102*
ubuntu/mozjs115*
Mozilla Firefox<134
134
Mozilla Thunderbird<128.6
128.6
debian/firefox
159.0.1-1
debian/firefox-esr
140.12.0esr-1~deb12u1153.6.0esr-1~deb12u2140.15.0esr-1~deb13u1153.6.0esr-1~deb13u1153.5.1esr-1153.6.0esr-1
debian/thunderbird
1:140.12.0esr-1~deb12u11:153.6.0esr-1~deb12u21:140.12.0esr-1~deb13u11:153.6.0esr-1~deb13u11:153.5.0esr-11:153.6.0esr-1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 134
  2. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 128.6
  3. Upgrade

    Upgrade ubuntu/firefox to a version that resolves this vulnerability.

    Fixed in 134.0+build1-0ubuntu0.20.04.1
  4. Upgrade

    Upgrade ubuntu/thunderbird to a version that resolves this vulnerability.

    Fixed in 1:140.7.1+build1-0ubuntu0.22.04.1
  5. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 134
  6. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 128.6
  7. Upgrade

    Upgrade debian/firefox to a version that resolves this vulnerability.

    Fixed in 159.0.1-1
  8. Upgrade

    Upgrade debian/firefox-esr to a version that resolves this vulnerability.

    Fixed in 140.12.0esr-1~deb12u1Fixed in 153.6.0esr-1~deb12u2Fixed in 140.15.0esr-1~deb13u1Fixed in 153.6.0esr-1~deb13u1Fixed in 153.5.1esr-1Fixed in 153.6.0esr-1
  9. Upgrade

    Upgrade debian/thunderbird to a version that resolves this vulnerability.

    Fixed in 1:140.12.0esr-1~deb12u1Fixed in 1:153.6.0esr-1~deb12u2Fixed in 1:140.12.0esr-1~deb13u1Fixed in 1:153.6.0esr-1~deb13u1Fixed in 1:153.5.0esr-1Fixed in 1:153.6.0esr-1
  10. Upgrade

    Upgrade Firefox to a version that resolves this vulnerability.

    Fixed in 134
  11. Upgrade

    Upgrade Thunderbird ESR to a version that resolves this vulnerability.

    Fixed in 128.6

Event History

Jan 7, 2025
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Data Sourced
via Ubuntu·12:00 AM
RemedyDescriptionSeverityAffected Software
CVE Published
via MITRE·04:07 PM
Data Sourced
via MITRE·04:07 PM
Description
Data Sourced
via OSV·04:15 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·04:15 PM
DescriptionSeverityWeaknessAffected Software
Data Sourced
via Red Hat·05:01 PM
DescriptionSeverityAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

What is the severity of CVE-2025-0239?

CVE-2025-0239 has been rated as a high severity vulnerability due to its impact on certificate validation during insecure redirects.

2

How do I fix CVE-2025-0239?

To fix CVE-2025-0239, update your Firefox or Thunderbird application to the latest version available, specifically version 134 or 128.6 for Firefox ESR.

3

Which versions of Firefox are affected by CVE-2025-0239?

CVE-2025-0239 affects Firefox versions prior to 134 and Firefox ESR versions prior to 128.6.

4

Is Thunderbird affected by CVE-2025-0239?

Yes, Thunderbird versions prior to 134 and 128.6 are affected by CVE-2025-0239.

5

What type of vulnerability is CVE-2025-0239?

CVE-2025-0239 is a security vulnerability related to improper certificate validation in Alt-Svc and ALPN.

Company

Resources

Contact

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