Integer overflow in the PL_ARENA_ALLOCATE implementation in Netscape Portable Runtime (NSPR) in Mozilla Network Security Services (NSS) before 3.19.2.1 and 3.20.x before 3.20.1, as used in Firefox before 42.0 and Firefox ESR 38.x before 38.4 and other products, allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via unspecified vectors.
Conclusion & alert: CVE-2015-7183 is rated Moderate Risk (64.8/100): CVSS High severity, with high exploitation likelihood (EPSS 6.85%, 93th percentile). Core evidence: EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +2.15% over the last day, indicating growing attacker interest. Mandatory action: High exploitation likelihood—assess exposure and prioritize remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-15 | 4.70% | 6.85% | +2.15% |
| 2 | 2026-03-03 | 5.02% | 4.70% | -0.32% |
| 3 | 2026-02-21 | — | 5.02% | — |
Full EPSS history (18 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 7.5 | 2.0 | HIGH |
|
10.0 | 6.4 | [email protected] |
| vendor | priority | summary | link |
|---|---|---|---|
debian
|
not yet assigned | CVE-2015-7183 not yet assigned priority: Debian including 2 source packages (nspr, virtualbox), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. | https://security-tracker.debian.org/tracker/CVE-2015-7183 |
gentoo
|
normal | CVE-2015-7183: 2 GLSA(s) (201512-10, 201605-06), 6 atom(s) (dev-libs/nspr, dev-libs/nss, mail-client/thunderbird, mail-client/thunderbird-bin, www-client/firefox, www-client/firefox-bin); latest impact normal. | https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2015-7183 |
redhat
|
critical | — | https://access.redhat.com/security/cve/CVE-2015-7183 |
suse
|
high | CVE-2015-7183 severity important: SUSE including 444 source package names (MozillaFirefox, MozillaFirefox-102.11.0-150200.152.87.1, …), 728 product×package rows across 99 product lines (Image SLES12-SP5-Azure-BYOS, Image SLES12-SP5-Azure-Basic-On-Demand, … (99 product lines)): Fixed 448, Known Affected 231, Known Not Affected 49. | https://www.suse.com/security/cve/CVE-2015-7183/ |
ubuntu
|
medium | CVE-2015-7183 medium priority: Ubuntu including 4 source packages (firefox, nspr, thunderbird, virtualbox), 32 status rows across 8 suites (precise, trusty, upstream, vivid, wily, xenial, yakkety, zesty): released 25, not-affected 6, ignored 1. | https://ubuntu.com/security/CVE-2015-7183 |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| mozilla | firefox | <= 41.0.2 | cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* |
| mozilla | network_security_services | <= 3.19.2.0 | cpe:2.3:a:mozilla:network_security_services:*:*:*:*:*:*:*:* |
| mozilla | network_security_services | 3.20.0 | cpe:2.3:a:mozilla:network_security_services:3.20.0:*:*:*:*:*:*:* |
| mozilla | firefox | 38.0 | cpe:2.3:a:mozilla:firefox:38.0:*:*:*:*:*:*:* |
| mozilla | firefox | 38.0.1 | cpe:2.3:a:mozilla:firefox:38.0.1:*:*:*:*:*:*:* |
| mozilla | firefox | 38.0.5 | cpe:2.3:a:mozilla:firefox:38.0.5:*:*:*:*:*:*:* |
| mozilla | firefox | 38.1.0 | cpe:2.3:a:mozilla:firefox:38.1.0:*:*:*:*:*:*:* |
| mozilla | firefox | 38.1.1 | cpe:2.3:a:mozilla:firefox:38.1.1:*:*:*:*:*:*:* |
| mozilla | firefox | 38.2.0 | cpe:2.3:a:mozilla:firefox:38.2.0:*:*:*:*:*:*:* |
| mozilla | firefox | 38.2.1 | cpe:2.3:a:mozilla:firefox:38.2.1:*:*:*:*:*:*:* |
| mozilla | firefox | 38.3.0 | cpe:2.3:a:mozilla:firefox:38.3.0:*:*:*:*:*:*:* |