NSS: incorrectly permited skipping of ServerKeyExchange (MFSA 2015-71)
Published Jul 6, 2015
4.3
MEDIUMCVSS 2.0
EPSS 3.28%
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.
Affected products
No data.
Configuration 1
- 12.0
- 12.04
- 14.04
- 14.10
- 15.04
- 7.0
- 8.0
- 12.0
- 11
- 12.0
Configuration 2
- 3.19
Running on/with
- ≤ 38.1.0
- 31.0
- 31.1.0
- 31.1.1
- 31.3.0
- 31.5.1
- 31.5.2
- 31.5.3
- 38.0
- 31.1
- 31.2
- 31.3
- 31.4
- 31.5
- 31.6.0
- 31.7.0
- ≤ 38.0.1
No data.
Red Hat Enterprise Linux 5
nss-0:3.19.1-1.el5_11
Fixed · RHSA-2015:1664
Red Hat Enterprise Linux 6
nss-0:3.19.1-3.el6_6
Fixed · RHSA-2015:1185
Red Hat Enterprise Linux 6
nss-util-0:3.19.1-1.el6_6
Fixed · RHSA-2015:1185
Red Hat Enterprise Linux 7
nss-0:3.19.1-3.ael7b_1
Fixed · RHSA-2015:1185
Red Hat Enterprise Linux 7
nss-util-0:3.19.1-1.ael7b_1
Fixed · RHSA-2015:1185
Red Hat Enterprise Linux 5
gnutls
Not affected
Red Hat Enterprise Linux 5
openssl
Not affected
Red Hat Enterprise Linux 6
gnutls
Not affected
Red Hat Enterprise Linux 6
openssl
Not affected
Red Hat Enterprise Linux 7
gnutls
Not affected
Red Hat Enterprise Linux 7
openssl
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 5 | nss-0:3.19.1-1.el5_11 | Fixed | RHSA-2015:1664 |
| Red Hat Enterprise Linux 6 | nss-0:3.19.1-3.el6_6 | Fixed | RHSA-2015:1185 |
| Red Hat Enterprise Linux 6 | nss-util-0:3.19.1-1.el6_6 | Fixed | RHSA-2015:1185 |
| Red Hat Enterprise Linux 7 | nss-0:3.19.1-3.ael7b_1 | Fixed | RHSA-2015:1185 |
| Red Hat Enterprise Linux 7 | nss-util-0:3.19.1-1.ael7b_1 | Fixed | RHSA-2015:1185 |
| Red Hat Enterprise Linux 5 | gnutls | Not affected | n/a |
| Red Hat Enterprise Linux 5 | openssl | Not affected | n/a |
| Red Hat Enterprise Linux 6 | gnutls | Not affected | n/a |
| Red Hat Enterprise Linux 6 | openssl | Not affected | n/a |
| Red Hat Enterprise Linux 7 | gnutls | Not affected | n/a |
| Red Hat Enterprise Linux 7 | openssl | Not affected | n/a |
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
No CVSS v4.0 score for this CVE.
No CVSS v3.1 score for this CVE.
No CVSS v3.0 score for this CVE.
AV:N/AC:M/Au:N/C:N/I:P/A:N
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (11 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 3.28% (0.03275) | 88.01th | v5 (v2026.06.15) |
| Jun 15, 2026 | 3.28% (0.03275) | 86.77th | v5 (v2026.06.15) |
| Mar 30, 2025 | 0.90% (0.00900) | 73.56th | v4 (v2025.03.14) |
| Mar 29, 2025 | 3.38% (0.03381) | 78.78th | v4 (v2025.03.14) |
| Mar 17, 2025 | 0.84% (0.00843) | 73.14th | v4 (v2025.03.14) |
| Dec 12, 2024 | 0.14% (0.00137) | 50.74th | v3 (v2023.03.01) |
| Mar 12, 2024 | 0.14% (0.00137) | 48.19th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.12% (0.00117) | 43.85th | v3 (v2023.03.01) |
| Mar 6, 2023 | 2.69% (0.02686) | 82.85th | v2 (v2022.01.01) |
| Apr 1, 2022 | 2.69% (0.02686) | 81.17th | v2 (v2022.01.01) |
| Feb 4, 2022 | 2.69% (0.02686) | 62.66th | v2 (v2022.01.01) |
References (33)
- http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00025.html vendor-advisoryx_refsource_SUSE
- http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00031.html vendor-advisoryx_refsource_SUSE
- http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00033.html vendor-advisoryx_refsource_SUSEThird Party Advisory
- http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00034.html vendor-advisoryx_refsource_SUSEThird Party Advisory
- http://lists.opensuse.org/opensuse-security-announce/2015-08/msg00021.html vendor-advisoryx_refsource_SUSE
- http://rhn.redhat.com/errata/RHSA-2015-1185.html vendor-advisoryx_refsource_REDHAT
- http://rhn.redhat.com/errata/RHSA-2015-1664.html vendor-advisoryx_refsource_REDHAT
- http://www.debian.org/security/2015/dsa-3324 vendor-advisoryx_refsource_DEBIANThird Party Advisory
- http://www.debian.org/security/2015/dsa-3336 vendor-advisoryx_refsource_DEBIANThird Party Advisory
- http://www.mozilla.org/security/announce/2015/mfsa2015-71.html x_refsource_CONFIRMVendor Advisory
- http://www.oracle.com/technetwork/security-advisory/cpuapr2016v3-2985753.html x_refsource_CONFIRMThird Party Advisory
- http://www.oracle.com/technetwork/security-advisory/cpujul2016-2881720.html x_refsource_CONFIRMThird Party Advisory
- http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html x_refsource_CONFIRMThird Party Advisory
- http://www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html x_refsource_CONFIRMThird Party Advisory
- http://www.oracle.com/technetwork/topics/security/ovmbulletinjul2016-3090546.html x_refsource_CONFIRMThird Party Advisory
- http://www.securityfocus.com/bid/75541 vdb-entryx_refsource_BID
- http://www.securityfocus.com/bid/83398 vdb-entryx_refsource_BID
- http://www.securityfocus.com/bid/91787 vdb-entryx_refsource_BIDThird Party Advisory
- http://www.securitytracker.com/id/1032783 vdb-entryx_refsource_SECTRACK
- http://www.securitytracker.com/id/1032784 vdb-entryx_refsource_SECTRACK
- http://www.ubuntu.com/usn/USN-2656-1 vendor-advisoryx_refsource_UBUNTU
- http://www.ubuntu.com/usn/USN-2656-2 vendor-advisoryx_refsource_UBUNTU
- http://www.ubuntu.com/usn/USN-2672-1 vendor-advisoryx_refsource_UBUNTU
- http://www.ubuntu.com/usn/USN-2673-1 vendor-advisoryx_refsource_UBUNTUThird Party Advisory
- https://access.redhat.com/security/cve/CVE-2015-2721 Vendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1086145 x_refsource_CONFIRMExploitIssue TrackingVDB EntryVendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1236967 Issue Tracking
- https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/NSS_3.19_release_notes x_refsource_CONFIRMRelease Notes
- https://nvd.nist.gov/vuln/detail/CVE-2015-2721
- https://security.gentoo.org/glsa/201512-10 vendor-advisoryx_refsource_GENTOO
- https://security.gentoo.org/glsa/201701-46 vendor-advisoryx_refsource_GENTOO
- https://smacktls.com x_refsource_MISCTechnical Description
- https://www.cve.org/CVERecord?id=CVE-2015-2721
Change history (0)
No recorded changes yet.