🛡️ CVE-2021-21704 on Debian — php7.4

⚪ Unknown ✅ No Known Exploit OSV

N/A

CVSS Score

0 Low4 Medium7 High9 Critical10

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.

Distribution advisory

This page covers CVE-2021-21704 as tracked by Debian, for the package php7.4. The fix is available in version 7.4.21-1+deb11u1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Affected software

DEBIAN-CVE-2021-21704 is recorded against 1 package.

php7.4 (fixed in 7.4.21-1+deb11u1)

Timeline and source

Published on 4 October 2021 and last revised on 4 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

CVE-2021-21704 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Base record Ubuntu

Details

Severity Unknown

CVSS Score N/A

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

CWE N/A

Public Exploit ✅ No

Source OSV

Published 2021-10-04

Updated 2026-08-20

Modified 2026-08-04

Fix URL N/A

Affected Packages

Software	From version	Fixed in
php7.4	—	7.4.21-1+deb11u1

References

ADVISORY https://security-tracker.debian.org/tracker/CVE-2021-21704

🔗 NVD 🔗 Mitre

Similar Threats

Vulnerability Monitoring

Track new vulnerabilities in php7.4

DEBIAN-CVE-2021-21704 is rated CVSS 5.0 Medium. BotEraser monitors your WordPress installation and notifies you when software you use appears in our vulnerability database.

Set Up Free Alerts →

No credit card required · Results in minutes

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.