Description
Mozilla Network Security Services (NSS) before 3.19, as used in Mozilla Firefox before 39.0, Firefox ESR 31.x before 31.8 and 38.x before 38.1, Thunderbird before 38.1, and other products, does not properly determine state transitions for the TLS state machine, which allows man-in-the-middle attackers to defeat cryptographic protection mechanisms by blocking messages, as demonstrated by removing a forward-secrecy property by blocking a ServerKeyExchange message, aka a "SMACK SKIP-TLS" issue.
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 | nss | 2:3.19.1-1 | — |
| Debian 13 | nss | 2:3.19.1-1 | — |
| Debian 12 | nss | 2:3.19.1-1 | — |
| Debian 8 | icedove | 31.8.0-1~deb8u1 | DSA-3324-1 |
| Debian 8 | iceweasel | 31.8.0esr-1~deb8u1 | DSA-3300-1 |
| Debian 8 | nss | 2:3.17.2-1.1+deb8u1 | DSA-3336-1 |
| Debian 7 | icedove | 31.8.0-1~deb7u1 | DSA-3324-1 |
| Debian 7 | iceweasel | 31.8.0esr-1~deb7u1 | DSA-3300-1 |
| Debian 7 | nss | 2:3.14.5-1+deb7u5 | DSA-3336-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 6.0 | nss | 3.12.8-1+squeeze12 | DLA-315-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 14.04 LTS | firefox | 39.0+build5-0ubuntu0.14.04.1 | USN-2656-1 |
| Ubuntu 14.04 LTS | nss | 2:3.19.2-0ubuntu0.14.04.1 | USN-2672-1 |
| Ubuntu 14.04 LTS | thunderbird | 1:31.8.0+build1-0ubuntu0.14.04.1 | USN-2673-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 7 | nss +4 | 3.19.1-3.ael7b_1 | RHSA-2015:1185 |
| RHEL 7 | nss-util +1 | 3.19.1-1.ael7b_1 | RHSA-2015:1185 |
| RHEL 6 | nss +4 | 3.19.1-3.el6_6 | RHSA-2015:1185 |
| RHEL 6 | nss-util +1 | 3.19.1-1.el6_6 | RHSA-2015:1185 |
| RHEL 5 | nss +3 | 3.19.1-1.el5_11 | RHSA-2015:1664 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 | MozillaFirefox | 31.8.0esr-37.3 | SUSE-SU-2015:1269-1 |
| SLES 12 | mozilla-nspr | 4.10.8-3.1 | SUSE-SU-2015:1269-1 |
| SLES 12 | mozilla-nss | 3.19.2_CKBI_1.98-21.1 | SUSE-SU-2015:1269-1 |
| SLES 11 SP4 | MozillaFirefox | 31.8.0esr-0.10.1 | SUSE-SU-2015:1268-2, SUSE-SU-2015:1268-1 |
| SLES 11 SP4 | mozilla-nspr | 4.10.8-0.5.1 | SUSE-SU-2015:1268-2, SUSE-SU-2015:1268-1 |
| SLES 11 SP4 | mozilla-nss | 3.19.2_CKBI_1.98-0.10.1 | SUSE-SU-2015:1268-2, SUSE-SU-2015:1268-1 |
| SLES 11 SP3 | MozillaFirefox | 31.8.0esr-0.10.1 | SUSE-SU-2015:1268-2 |
| SLES 11 SP3 | mozilla-nspr | 4.10.8-0.5.1 | SUSE-SU-2015:1268-2 |
| SLES 11 SP3 | mozilla-nss | 3.19.2_CKBI_1.98-0.10.1 | SUSE-SU-2015:1268-2 |
| SLES 11 SP2 | MozillaFirefox | 38.2.0esr-10.1 | SUSE-SU-2015:1449-1 |
| SLES 11 SP2 | MozillaFirefox-branding-SLED | 31.0-0.5.7.11 | SUSE-SU-2015:1449-1 |
| SLES 11 SP2 | firefox-gcc47 | 4.7.2_20130108-0.37.2 | SUSE-SU-2015:1449-1 |
| SLES 11 SP2 | mozilla-nss | 3.19.2.0-0.7.1 | SUSE-SU-2015:1449-1 |
| SLES 11 SP1 | MozillaFirefox | 38.2.0esr-10.1 | SUSE-SU-2015:1449-1 |
| SLES 11 SP1 | MozillaFirefox-branding-SLED | 31.0-0.5.7.11 | SUSE-SU-2015:1449-1 |
| SLES 11 SP1 | firefox-gcc47 | 4.7.2_20130108-0.37.2 | SUSE-SU-2015:1449-1 |
| SLES 11 SP1 | mozilla-nss | 3.19.2.0-0.7.1 | SUSE-SU-2015:1449-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 | MozillaFirefox | 31.8.0esr-37.3 | SUSE-SU-2015:1269-1 |
| SLES for SAP 12 | mozilla-nspr | 4.10.8-3.1 | SUSE-SU-2015:1269-1 |
| SLES for SAP 12 | mozilla-nss | 3.19.2_CKBI_1.98-21.1 | SUSE-SU-2015:1269-1 |
| SLES for SAP 11 SP4 | MozillaFirefox | 31.8.0esr-0.10.1 | SUSE-SU-2015:1268-2, SUSE-SU-2015:1268-1 |
| SLES for SAP 11 SP4 | mozilla-nspr | 4.10.8-0.5.1 | SUSE-SU-2015:1268-2, SUSE-SU-2015:1268-1 |
| SLES for SAP 11 SP4 | mozilla-nss | 3.19.2_CKBI_1.98-0.10.1 | SUSE-SU-2015:1268-2, SUSE-SU-2015:1268-1 |
| SLES for SAP 11 SP3 | MozillaFirefox | 31.8.0esr-0.10.1 | SUSE-SU-2015:1268-2 |
| SLES for SAP 11 SP3 | mozilla-nspr | 4.10.8-0.5.1 | SUSE-SU-2015:1268-2 |
| SLES for SAP 11 SP3 | mozilla-nss | 3.19.2_CKBI_1.98-0.10.1 | SUSE-SU-2015:1268-2 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | MozillaFirefox | 50.1.0-1.1 | openSUSE-SU-2024:10071-1 |
| openSUSE Tumbleweed | MozillaThunderbird | 45.5.1-1.1 | openSUSE-SU-2024:10230-1 |
| openSUSE Tumbleweed | firefox-esr | 128.5.1-1.1 | openSUSE-SU-2024:14572-1 |
| openSUSE Tumbleweed | mozilla-nss | 3.26.2-1.1 | openSUSE-SU-2024:10451-1 |
Advisories 17
- RHSA-2015:1185 Red Hat Security Advisory: nss security update Red Hat Security Advisories (RHSA) · Jun 29, 2026
- RHSA-2015:1664 Red Hat Security Advisory: nss security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Jun 27, 2026
- USN-2656-1 firefox vulnerabilities Ubuntu Security Notices (USN) · May 29, 2026
- USN-2673-1 thunderbird vulnerabilities Ubuntu Security Notices (USN) · May 29, 2026
- USN-2672-1 nss vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DSA-3300-1 iceweasel - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3336-1 nss - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3324-1 icedove - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-315-1 nss - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10451-1 libfreebl3-3.26.2-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10230-1 MozillaThunderbird-45.5.1-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2015:1268-2 Security update for MozillaFirefox, mozilla-nspr, mozilla-nss SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2015:1268-1 Security update for MozillaFirefox, mozilla-nspr, mozilla-nss SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2015:1449-1 Security update for MozillaFirefox, mozilla-nss SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2015:1269-1 Security update for MozillaFirefox, mozilla-nspr, mozilla-nss 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-2024:10071-1 MozillaFirefox-50.1.0-1.1 on GA media SUSE / openSUSE Security Updates · May 7, 2025
References
- http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html
- openSUSE-SU-2015:1229 vendor-advisory
- SUSE-SU-2015:1268 vendor-advisory
- https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/NSS_3.19_release_notes
- 83398 vdb-entry
- GLSA-201512-10 vendor-advisory
- GLSA-201701-46 vendor-advisory
- DSA-3336 vendor-advisory
- http://www.oracle.com/technetwork/security-advisory/cpujul2016-2881720.html
- 75541 vdb-entry
- RHSA-2015:1185 vendor-advisory
- http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
- DSA-3324 vendor-advisory
- USN-2672-1 vendor-advisory
- USN-2673-1 vendor-advisory
- 1032784 vdb-entry
- https://bugzilla.mozilla.org/show_bug.cgi?id=1086145
- SUSE-SU-2015:1269 vendor-advisory
- http://www.mozilla.org/security/announce/2015/mfsa2015-71.html
- http://www.oracle.com/technetwork/security-advisory/cpuapr2016v3-2985753.html
- 91787 vdb-entry
- openSUSE-SU-2015:1266 vendor-advisory
- RHSA-2015:1664 vendor-advisory
- USN-2656-1 vendor-advisory
- SUSE-SU-2015:1449 vendor-advisory
- https://smacktls.com
- 1032783 vdb-entry
- USN-2656-2 vendor-advisory
- http://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html