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Vulnerability record · CVE-2021-21704 · published 4 October 2021

CVE-2021-21704: Php out-of-bounds read vulnerability

Php · Php

In PHP versions 7.3.x below 7.3.29, 7.4.x below 7.4.21 and 8.0.x below 8.0.8, when using Firebird PDO driver extension, a malicious database server could cause crashes in various database functions, such as getAttribute(), execute(), fetch() and others by returning invalid response data that is not parsed correctly by the driver. This can result in crashes, denial of service or potentially memory corruption.

5.9 CVSS 3.1 Medium EPSS 1.8% · top 22.4% CWE-125 · Out-of-bounds readCWE-190 · Integer overflow
5.9CVSS 3.1 base score, v2 4.3
1.8%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
12References, 8 tagged exploit
17 Jun 2026Last modified by NVD

Description

In PHP versions 7.3.x below 7.3.29, 7.4.x below 7.4.21 and 8.0.x below 8.0.8, when using Firebird PDO driver extension, a malicious database server could cause crashes in various database functions, such as getAttribute(), execute(), fetch() and others by returning invalid response data that is not parsed correctly by the driver. This can result in crashes, denial of service or potentially memory corruption.

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

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://bugs.php.net/bug.php?id=76448 ExploitIssue TrackingPatchVendor Advisory
https://bugs.php.net/bug.php?id=76449 ExploitIssue TrackingPatchVendor Advisory
https://bugs.php.net/bug.php?id=76450 ExploitIssue TrackingPatchVendor Advisory
https://bugs.php.net/bug.php?id=76452 ExploitIssue TrackingPatchVendor Advisory
https://security.gentoo.org/glsa/202209-20 Third Party Advisory
https://security.netapp.com/advisory/ntap-20211029-0006/ Third Party Advisory
https://bugs.php.net/bug.php?id=76448 ExploitIssue TrackingPatchVendor Advisory
https://bugs.php.net/bug.php?id=76449 ExploitIssue TrackingPatchVendor Advisory
https://bugs.php.net/bug.php?id=76450 ExploitIssue TrackingPatchVendor Advisory
https://bugs.php.net/bug.php?id=76452 ExploitIssue TrackingPatchVendor Advisory
https://security.gentoo.org/glsa/202209-20 Third Party Advisory
https://security.netapp.com/advisory/ntap-20211029-0006/ Third Party Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-21704), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.