Description
During TLS 1.2 exchanges, handshake hashes are generated which point to a message buffer. This saved data is used for later messages but in some cases, the handshake transcript can exceed the space available in the current buffer, causing the allocation of a new buffer. This leaves a pointer pointing to the old, freed buffer, resulting in a use-after-free when handshake hashes are then calculated afterwards. This can result in a potentially exploitable crash. This vulnerability affects Firefox < 56, Firefox ESR < 52.4, and Thunderbird < 52.4.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mozilla | Firefox | unspecified – < 56 | 56 |
| Mozilla | Firefox ESR | unspecified – < 52.4 | 52.4 |
| Mozilla | Thunderbird | unspecified – < 52.4 | 52.4 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | firefox-esr | 52.4.0esr-2 | — |
| Debian 14 | nss | 2:3.33-1 | — |
| Debian 14 | thunderbird | 1:52.4.0-1 | — |
| Debian 13 | firefox-esr | 52.4.0esr-2 | — |
| Debian 13 | nss | 2:3.33-1 | — |
| Debian 13 | thunderbird | 1:52.4.0-1 | — |
| Debian 12 | firefox-esr | 52.4.0esr-2 | — |
| Debian 12 | nss | 2:3.33-1 | — |
| Debian 12 | thunderbird | 1:52.4.0-1 | — |
| Debian 9 | firefox-esr | 52.4.0esr-1~deb9u1 | DSA-3987-1 |
| Debian 9 | nss | 2:3.26.2-1.1+deb9u1 | DSA-3998-1 |
| Debian 9 | thunderbird | 1:52.4.0-1~deb9u1 | DSA-4014-1 |
| Debian 8 | firefox-esr | 52.4.0esr-1~deb8u1 | DSA-3987-1 |
| Debian 8 | nss | 2:3.26-1+debu8u3 | DSA-3998-1 |
| Debian 8 | thunderbird | 1:52.4.0-1~deb8u1 | DSA-4014-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 7 | firefox-esr | 52.4.0esr-2~deb7u1 | DLA-1118-1 |
| Debian 7 | nss | 2:3.26-1+debu7u5 | DLA-1138-1 |
| Debian 7 | thunderbird | 1:52.4.0-1~deb7u1 | DLA-1153-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | firefox | 56.0+build6-0ubuntu1 | — |
| Ubuntu 18.04 LTS | nss | 2:3.32-1ubuntu3 | — |
| Ubuntu 18.04 LTS | thunderbird | 1:52.4.0+build1-0ubuntu2 | — |
| Ubuntu 16.04 LTS | firefox | 56.0+build6-0ubuntu0.16.04.1 | USN-3435-1 |
| Ubuntu 16.04 LTS | nss | 2:3.28.4-0ubuntu0.16.04.3 | USN-3431-1 |
| Ubuntu 16.04 LTS | thunderbird | 1:52.4.0+build1-0ubuntu0.16.04.2 | USN-3436-1 |
| Ubuntu 14.04 LTS | firefox | 56.0+build6-0ubuntu0.14.04.1 | USN-3435-1 |
| Ubuntu 14.04 LTS | nss | 2:3.28.4-0ubuntu0.14.04.3 | USN-3431-1 |
| Ubuntu 14.04 LTS | thunderbird | 1:52.4.0+build1-0ubuntu0.14.04.2 | USN-3436-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 7 | nss +4 | 3.28.4-12.el7_4 | RHSA-2017:2832 |
| RHEL 6 | nss +4 | 3.28.4-4.el6_9 | RHSA-2017:2832 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP3 | MozillaFirefox | 52.4.0esr-109.6.2 | SUSE-SU-2017:2688-1 |
| SLES 12 SP3 | mozilla-nss | 3.29.5-58.3.1 | SUSE-SU-2017:2688-1 |
| SLES 12 SP2 | MozillaFirefox | 52.4.0esr-109.6.2 | SUSE-SU-2017:2688-1 |
| SLES 12 SP2 | mozilla-nss | 3.29.5-58.3.1 | SUSE-SU-2017:2688-1 |
| SLES 12 SP1 | MozillaFirefox | 52.4.0esr-109.6.2 | SUSE-SU-2017:2688-1 |
| SLES 12 SP1 | mozilla-nss | 3.29.5-58.3.1 | SUSE-SU-2017:2688-1 |
| SLES 12 | MozillaFirefox | 52.4.0esr-109.6.2 | SUSE-SU-2017:2688-1 |
| SLES 12 | mozilla-nss | 3.29.5-58.3.1 | SUSE-SU-2017:2688-1 |
| SLES 11 SP4 | MozillaFirefox | 52.4.0esr-72.13.2 | SUSE-SU-2017:2872-2, SUSE-SU-2017:2872-1 |
| SLES 11 SP4 | mozilla-nss | 3.29.5-47.6.1 | SUSE-SU-2017:2872-2, SUSE-SU-2017:2872-1 |
Show 8 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 11 SP3 | MozillaFirefox | 52.4.0esr-72.13.2 | SUSE-SU-2017:2872-2, SUSE-SU-2017:2872-1 |
| SLES 11 SP3 | mozilla-nss | 3.29.5-47.6.1 | SUSE-SU-2017:2872-2, SUSE-SU-2017:2872-1 |
| SLES for SAP 12 SP3 | MozillaFirefox | 52.4.0esr-109.6.2 | SUSE-SU-2017:2688-1 |
| SLES for SAP 12 SP3 | mozilla-nss | 3.29.5-58.3.1 | SUSE-SU-2017:2688-1 |
| SLES for SAP 12 SP2 | MozillaFirefox | 52.4.0esr-109.6.2 | SUSE-SU-2017:2688-1 |
| SLES for SAP 12 SP2 | mozilla-nss | 3.29.5-58.3.1 | SUSE-SU-2017:2688-1 |
| SLES for SAP 12 SP1 | MozillaFirefox | 52.4.0esr-109.6.2 | SUSE-SU-2017:2688-1 |
| SLES for SAP 12 SP1 | mozilla-nss | 3.29.5-58.3.1 | SUSE-SU-2017:2688-1 |
| SLES for SAP 11 SP4 | MozillaFirefox | 52.4.0esr-72.13.2 | SUSE-SU-2017:2872-2, SUSE-SU-2017:2872-1 |
| SLES for SAP 11 SP4 | mozilla-nss | 3.29.5-47.6.1 | SUSE-SU-2017:2872-2, SUSE-SU-2017:2872-1 |
| SUSE Package Hub 12 | MozillaThunderbird | 52.4.0-45.1 | openSUSE-SU-2017:2710-1, openSUSE-SU-2017:2707-1 |
| SUSE OpenStack Cloud 6 | MozillaFirefox | 52.4.0esr-109.6.2 | SUSE-SU-2017:2688-1 |
| SUSE OpenStack Cloud 6 | mozilla-nss | 3.29.5-58.3.1 | SUSE-SU-2017:2688-1 |
| SUSE Linux Enterprise Point of Sale 11 SP3 | MozillaFirefox | 52.4.0esr-72.13.2 | SUSE-SU-2017:2872-1 |
| SUSE Linux Enterprise Point of Sale 11 SP3 | mozilla-nss | 3.29.5-47.6.1 | SUSE-SU-2017:2872-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaFirefox | 92.0-1.2 | openSUSE-SU-2024:10600-1 |
| openSUSE Tumbleweed | MozillaThunderbird | 91.1.1-1.1 | openSUSE-SU-2024:10601-1 |
| openSUSE Tumbleweed | firefox-esr | 128.5.1-1.1 | openSUSE-SU-2024:14572-1 |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 7 | nss +4 | 3.28.4-12.el7_4 | ELSA-2017-2832 |
Advisories 19
- RHSA-2017:2832 Red Hat Security Advisory: nss security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- USN-3436-1 thunderbird vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- USN-3435-1 firefox vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- USN-3431-1 nss vulnerability Ubuntu Security Notices (USN) · Apr 22, 2026
- DSA-3998-1 nss - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-4014-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3987-1 firefox-esr - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-1118-1 firefox-esr - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-1153-1 thunderbird - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-1138-1 nss - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2017:2872-1 Security update for MozillaFirefox, mozilla-nss SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:2872-2 Security update for MozillaFirefox, mozilla-nss SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2017:2710-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:2688-1 Security update for MozillaFirefox, mozilla-nss SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10600-1 MozillaFirefox-92.0-1.2 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:14572-1 firefox-esr-128.5.1-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2017:2707-1 Security update for MozillaThunderbird SUSE / openSUSE Security Updates · May 7, 2025
- openSUSE-SU-2024:10601-1 MozillaThunderbird-91.1.1-1.1 on GA media SUSE / openSUSE Security Updates · May 7, 2025
- ELSA-2017-2832 Important: nss security update (Oracle Linux 7) Oracle Linux Security Advisories (ELSA) · Sep 28, 2017
References
- RHSA-2017:2832 vendor-advisory
- 101059 vdb-entry
- [debian-lts-announce] 20171101 [SECURITY] [DLA 1153-1] icedove/thunderbird security update mailing-list
- https://www.mozilla.org/security/advisories/mfsa2017-22/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1377618
- 1039465 vdb-entry
- https://www.mozilla.org/security/advisories/mfsa2017-21/
- DSA-4014 vendor-advisory
- http://www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.html
- https://www.mozilla.org/security/advisories/mfsa2017-23/
- DSA-3998 vendor-advisory
- DSA-3987 vendor-advisory
- GLSA-201803-14 vendor-advisory