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CVE-2017-8923

CRITICALCVSS 9.8/10EPSS 7.19%

Last modified

CVE-2017-8923 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. The zend_string_extend function in Zend/zend_string.h in PHP through 7.1.5 does not prevent changes to string objects that result in a negative length, which allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact by leveraging a script's use of .= with a long string.. EPSS estimates a 7.19% chance of exploitation in the next 30 days.

Description

The zend_string_extend function in Zend/zend_string.h in PHP through 7.1.5 does not prevent changes to string objects that result in a negative length, which allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact by leveraging a script's use of .= with a long string.

Metrics

CVSS 3.1
9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability
7.19%

93.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
PhpPhp< 7.4.24
PhpPhp>= 8.0.0, < 8.0.11

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2017-8923?
The zend_string_extend function in Zend/zend_string.h in PHP through 7.1.5 does not prevent changes to string objects that result in a negative length, which allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact by leveraging a script's use of .= with a long string.
How severe is CVE-2017-8923?
CVE-2017-8923 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 7.19% probability of exploitation in the next 30 days.
How do I fix CVE-2017-8923?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

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Source: NVD / NIST