CVE-2007-1661

CVE-2007-1661 is a medium-severity vulnerability in Pcre Perl-compatible Regular Expression Library with a CVSS 2.0 base score of 6.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Description

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.

Frequently asked questions

What is CVE-2007-1661?
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.
How severe is CVE-2007-1661?
CVE-2007-1661 has a CVSS 2.0 base score of 6.4, rated medium severity.
Is CVE-2007-1661 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (83rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2007-1661?
CVE-2007-1661 primarily affects Pcre Perl-compatible Regular Expression Library. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2007-1661?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2007-1661 published?
CVE-2007-1661 was published on 2007-11-07 and last updated on 2026-06-16.

References

Affected products (5)