CVE-2021-21704

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. Limited direct impact.

Exploit odds

1.8% chance of exploitation in the next 30 days (EPSS).

Fix

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

Timeline

1. 2021-10-04 04:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:36 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.8% in the next 30 days (EPSS).
• Severity: 5.0 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-10-04 04:15 UTC

Last modified

2026-06-17 03:36 UTC

Exploit probability

1.8% · EPSS, next 30 days

Weakness

CWE-125 · Out-of-bounds read

Record status

Modified

Affected

• PHP < 7.3.29
• PHP < 7.4.21
• PHP < 8.0.8
• Netapp Clustered Data Ontap

Attack profile CVSS 3.1 · 5.0

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

Low

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-2021-21704.md and follow it. Check whether this project is affected by CVE-2021-21704. 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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