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CVE-2006-1991

18
FAUCET Score

CVE-2006-1991 describes a denial-of-service vulnerability in the substr_compare function within PHP version 5.1.2. Attackers can trigger a memory access violation by providing an out-of-bounds offset argument, leading to system instability. With a CVSS score of 6.4, this vulnerability is of medium severity, requiring no authentication and having a low attack complexity, potentially impacting availability and integrity. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
5.1.2CPE matchmatch criteria
cpe:2.3:a:php:php:5.1.2:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

6.4MEDIUM

AV:N/AC:L/Au:N/C:N/I:P/A:P

Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Exploitability Score
10.0
Impact Score
4.9
CvssVersion
2.0

Exploit Intelligence

EPSS Score
2.19%
Probability of exploitation in next 30 days
EPSS Percentile
80.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0219 is in the 70th percentile among its peer group of 23,723 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

secunia.com / advisories/20052
Vendor Advisory
secunia.com / advisories/20269
PatchVendor Advisory
secunia.com / advisories/20676
Vendor Advisory
secunia.com / advisories/21125
Vendor Advisory
security.gentoo.org / glsa/glsa-200605-08.xml
securitytracker.com / id
exchange.xforce.ibmcloud.com / vulnerabilities/26003
infigo.hr / en/in_focus/advisories/INFIGO-2006-04-02
Exploit
mandriva.com / security/advisories
novell.com / linux/security/advisories/2006_31_php.html
ubuntu.com / usn/usn-320-1
vupen.com / english/advisories/2006/1500
Vendor Advisory