Perl-Compatible Regular Expression (PCRE) library before 7.3 backtracks too far when matching certain input bytes against some regex patterns in non-UTF-8 mode, which allows context-dependent attackers to obtain sensitive information or cause a denial of service (crash), as demonstrated by the "\X?\d" and "\P{L}?\d" patterns.
Conclusion & alert: CVE-2007-1661 is rated Moderate Risk (54.9/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.49%). Mandatory action: Review affected assets and schedule 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 | 2.03% | 2.49% | +0.46% |
| 2 | 2026-03-15 | 2.72% | 2.03% | -0.68% |
| 3 | 2025-03-30 | — | 2.72% | — |
Full EPSS history (15 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 6.4 | 2.0 | MEDIUM |
|
10.0 | 4.9 | [email protected] |
| vendor | priority | summary | link |
|---|---|---|---|
debian
|
unimportant | CVE-2007-1661 unimportant priority: Debian including 2 source packages (glib2.0, pcre3), 7 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 7. | https://security-tracker.debian.org/tracker/CVE-2007-1661 |
gentoo
|
normal | CVE-2007-1661: 1 GLSA(s) (200711-30), 1 atom(s) (dev-libs/libpcre); latest impact normal. | https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2007-1661 |
redhat
|
high | — | https://access.redhat.com/security/cve/CVE-2007-1661 |
ubuntu
|
low | CVE-2007-1661 low priority: Ubuntu including 1 source packages (pcre3), 5 status rows across 5 suites (dapper, edgy, feisty, gutsy, upstream): released 5. | https://ubuntu.com/security/CVE-2007-1661 |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| pcre | perl-compatible_regular_expression_library | <= 7.2 | cpe:2.3:a:pcre:perl-compatible_regular_expression_library:*:*:*:*:*:*:*:* |
| pcre | perl-compatible_regular_expression_library | 7.0 | cpe:2.3:a:pcre:perl-compatible_regular_expression_library:7.0:*:*:*:*:*:*:* |
| pcre | perl-compatible_regular_expression_library | 7.1 | cpe:2.3:a:pcre:perl-compatible_regular_expression_library:7.1:*:*:*:*:*:*:* |
| apple | mac_os_x | 10.4.11 | cpe:2.3:o:apple:mac_os_x:10.4.11:*:*:*:*:*:*:* |
| apple | mac_os_x_server | 10.4.11 | cpe:2.3:o:apple:mac_os_x_server:10.4.11:*:*:*:*:*:*:* |