CVE-2021-21704 — Out-of-bounds Read in Group PHP

CWE-125 — Out-of-bounds ReadCWE-190 — Integer Overflow or WraparoundCWE-787 — Out-of-bounds WriteCWE-20 — Improper Input ValidationCWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer17 documents8 sources
Severity
5.9MEDIUMNVD
CNA5.0
EPSS
0.1%
top 64.47%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
PHP Group PHPPHP
Timeline
PublishedOct 4
Latest updateMar 24

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 vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HExploitability: 2.2 | Impact: 3.6

Affected Packages2 packages

▶NVDphp/php7.3.0 — 7.3.29+2
▶CVEListV5php_group/php7.3.x — 7.3.29+2

Patches

Patch: bugs.php.net ↗Patch: bugs.php.net ↗Patch: bugs.php.net ↗

🔴Vulnerability Details

11
OSV
linux-azure, linux-azure-4.15 vulnerabilities↗2026-03-24
▶
OSV
linux-azure vulnerabilities↗2026-03-24
▶
OSV
linux-azure-fips vulnerabilities↗2026-03-24
▶
OSV
linux-aws-fips, linux-fips, linux-gcp-fips vulnerabilities↗2026-03-20
▶
OSV
linux, linux-aws, linux-aws-hwe, linux-gcp, linux-gcp-4.15, linux-hwe, linux-kvm, linux-oracle vulnerabilities↗2026-03-20
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📋Vendor Advisories

5
Microsoft
Multiple vulnerabilities in Firebird client extension↗2021-10-12
▶
Ubuntu
PHP vulnerabilities↗2021-07-13
▶
Ubuntu
PHP vulnerabilities↗2021-07-07
▶
Red Hat
php: security issues in pdo_firebase module↗2021-07-01
▶
Debian
CVE-2021-21704: php7.4 - 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, wh...↗2021
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CVE-2021-21704 — Out-of-bounds Read in PHP Group PHP | cvebase