CVE-2007-1661

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

2.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2007-11-07 23:46 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-16 22:38 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 2.5% in the next 30 days (EPSS).
• Severity: 6.4 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2007-11-07 23:46 UTC

Last modified

2026-06-16 22:38 UTC

Exploit probability

2.5% · EPSS, next 30 days

Record status

Modified

Affected

• Pcre perl-compatible Regular Expression Library ≤ 7.2
• Pcre perl-compatible Regular Expression Library 7.0
• Pcre perl-compatible Regular Expression Library 7.1
• Apple Mac Os X 10.4.11
• Apple Mac Os X Server 10.4.11

Attack profile CVSS 2.0 · 6.4

Attack vector

Network

Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

None

Availability

Partial

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2007-1661.md and follow it. Check whether this project is affected by CVE-2007-1661. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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