CVE-2025-0239
published 2025-01-07CVE-2025-0239: 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…
PriorityP414medium4CVSS 3.1
AVLACLPRNUINSUCNILAN
EPSS
0.23%
13.5th percentile
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.
Affected
13 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | firefox | < firefox 134.0-1 (sid) | firefox 134.0-1 (sid) |
| debian | firefox-esr | < firefox 134.0-1 (sid) | firefox 134.0-1 (sid) |
| debian | thunderbird | < firefox 134.0-1 (sid) | firefox 134.0-1 (sid) |
| mozilla | firefox | < 128.6.0 | 128.6.0 |
| mozilla | firefox | < 134.0 | 134.0 |
| mozilla | firefox | — | — |
| mozilla | firefox | >= 0 < 134.0+build1-0ubuntu0.20.04.1 | 134.0+build1-0ubuntu0.20.04.1 |
| mozilla | thunderbird | < 128.6.0 | 128.6.0 |
| mozilla | thunderbird | >= 0 < 1:128.6.0esr-1~deb11u1 | 1:128.6.0esr-1~deb11u1 |
| mozilla | thunderbird | >= 0 < 1:128.6.0esr-1~deb12u1 | 1:128.6.0esr-1~deb12u1 |
| mozilla | thunderbird | >= 0 < 1:128.6.0esr-1 | 1:128.6.0esr-1 |
| mozilla | thunderbird | >= 0 < 1:128.6.0esr-1 | 1:128.6.0esr-1 |
| mozilla | thunderbird | >= 129.0 < 134.0 | 134.0 |
CVSS provenance
nvdv3.14.0MEDIUMCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
osv5.4MEDIUM
vendor_ubuntu5.4MEDIUM
vendor_debian4.0MEDIUM
vendor_redhat4.0MEDIUM
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Ubuntu
Thunderbird vulnerabilities
vendor_ubuntu·2026-02-02
CVE-2025-8031 Thunderbird vulnerabilities
Title: Thunderbird vulnerabilities
Summary: Several security issues were fixed in Thunderbird.
Multiple security issues were discovered in Thunderbird. If a user were
tricked into opening a specially crafted website in a browsing context,
an attacker could potentially exploit these to cause a denial of service,
obtain sensitive information, bypass security restrictions, cross-site
tracing, or execute arbitrary code.
Instructions: In general, a standard system update will make all the necessary changes.
Ubuntu
Firefox vulnerabilities
vendor_ubuntu·2025-01-09·CVSS 5.4
CVE-2025-0240 [MEDIUM] Firefox vulnerabilities
Title: Firefox vulnerabilities
Summary: Several security issues were fixed in Firefox.
Multiple security issues were discovered in Firefox. If a user were
tricked into opening a specially crafted website, an attacker could
potentially exploit these to cause a denial of service, obtain sensitive
information across domains, or execute arbitrary code. (CVE-2025-0237,
CVE-2025-0239, CVE-2025-0240, CVE-2025-0242, CVE-2025-0243, CVE-2025-0247)
Irvan Kurniawan discovered that Firefox incorrectly handled memory when
breaking lines in text, leading to a use-after-free vulnerability. An
attacker could possibly use this issue to cause a denial of service or
possibly execute arbitrary code. (CVE-2025-0238)
Nils Bars discovered that Firefox incorrectly handled memory when using
JavaScript Text Segm
Red Hat
firefox: Alt-Svc ALPN validation failure when redirected
vendor_redhat·2025-01-07·CVSS 4.0
CVE-2025-0239 [MEDIUM] CWE-601 firefox: Alt-Svc ALPN validation failure when redirected
firefox: Alt-Svc ALPN validation failure when redirected
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.
A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue: When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site.
Statement: Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Package: firefox (Red Hat Enterprise Linux 10) - Affected
Package: firefox-flatpak-container (Red Hat Enterprise Linux 10) - Affected
Package: thunder
Debian
CVE-2025-0239: firefox - When using Alt-Svc, ALPN did not properly validate certificates when the origina...
vendor_debian·2025·CVSS 4.0
CVE-2025-0239 [MEDIUM] CVE-2025-0239: firefox - When using Alt-Svc, ALPN did not properly validate certificates when the origina...
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.
Scope: local
sid: resolved (fixed in 134.0-1)
Mozilla
Mozilla Foundation Security Advisory 2025-01: CVE-2025-0239
vendor_mozilla·CVSS 4.0
CVE-2025-0239 [MEDIUM] Mozilla Foundation Security Advisory 2025-01: CVE-2025-0239
Mozilla Foundation Security Advisory 2025-01
CVE: CVE-2025-0239
Product: Firefox
Impact: high
Fixed in: Firefox 134
Mozilla
Mozilla Foundation Security Advisory 2025-04: CVE-2025-0239
vendor_mozilla·CVSS 4.0
CVE-2025-0239 [MEDIUM] Mozilla Foundation Security Advisory 2025-04: CVE-2025-0239
Mozilla Foundation Security Advisory 2025-04
CVE: CVE-2025-0239
Product: Thunderbird
Impact: high
Fixed in: Thunderbird 134
Mozilla
Mozilla Foundation Security Advisory 2025-02: CVE-2025-0239
vendor_mozilla·CVSS 4.0
CVE-2025-0239 [MEDIUM] Mozilla Foundation Security Advisory 2025-02: CVE-2025-0239
Mozilla Foundation Security Advisory 2025-02
CVE: CVE-2025-0239
Product: Firefox ESR
Impact: moderate
Fixed in: Firefox ESR 128.6
Mozilla
Mozilla Foundation Security Advisory 2025-05: CVE-2025-0239
vendor_mozilla·CVSS 4.0
CVE-2025-0239 [MEDIUM] Mozilla Foundation Security Advisory 2025-05: CVE-2025-0239
Mozilla Foundation Security Advisory 2025-05
CVE: CVE-2025-0239
Product: Thunderbird
Impact: moderate
Fixed in: Thunderbird 128.6
OSV
firefox vulnerabilities
osv·2025-01-09·CVSS 5.4
CVE-2025-0237 [MEDIUM] firefox vulnerabilities
firefox vulnerabilities
Multiple security issues were discovered in Firefox. If a user were
tricked into opening a specially crafted website, an attacker could
potentially exploit these to cause a denial of service, obtain sensitive
information across domains, or execute arbitrary code. (CVE-2025-0237,
CVE-2025-0239, CVE-2025-0240, CVE-2025-0242, CVE-2025-0243, CVE-2025-0247)
Irvan Kurniawan discovered that Firefox incorrectly handled memory when
breaking lines in text, leading to a use-after-free vulnerability. An
attacker could possibly use this issue to cause a denial of service or
possibly execute arbitrary code. (CVE-2025-0238)
Nils Bars discovered that Firefox incorrectly handled memory when using
JavaScript Text Segmentation. An attacker could possibly use this issue to
cause a d
GHSA
GHSA-p4q7-g7ff-823j: When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site
ghsa_unreviewed·2025-01-07
CVE-2025-0239 [MEDIUM] CWE-295 GHSA-p4q7-g7ff-823j: When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site
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.
OSV
CVE-2025-0239: When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site
osv·2025-01-07·CVSS 4.0
CVE-2025-0239 [MEDIUM] CVE-2025-0239: When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site
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.
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
https://bugzilla.mozilla.org/show_bug.cgi?id=1929156https://www.mozilla.org/security/advisories/mfsa2025-01/https://www.mozilla.org/security/advisories/mfsa2025-02/https://www.mozilla.org/security/advisories/mfsa2025-04/https://www.mozilla.org/security/advisories/mfsa2025-05/https://lists.debian.org/debian-lts-announce/2025/01/msg00004.html
2025-01-07
Published