Is CVE-2021-21704 in the CISA KEV catalog?

No. CVE-2021-21704 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-21704?

CVE-2021-21704 has a CVSS v3 base score of 5.0 (MEDIUM).

What is the EPSS score for CVE-2021-21704?

CVE-2021-21704 has an EPSS score of 1.72% (75th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-21704?

Upgrade php7.4 on debian 11 to 7.4.21-1+deb11u1 or later. Fixes are available for 21 affected products.

CVE & CISA-KEV Catalog

CVE-2021-21704

MEDIUMEPSS 75th pctl

5.0

CVSS v3

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.

CWE-125Out-of-bounds Read CWE-190Integer Overflow CWE-787Out-of-bounds Write

How to fix

Remediation Available

php7.4Debian

Fixed in:7.4.21-1+deb11u1CVE-2021-21704

libapache2-mod-php5Ubuntu

Fixed in:5.5.9+dfsg-1ubuntu4.29+esm14USN-5006-2

libapache2-mod-php7.0Ubuntu

Fixed in:7.0.33-0ubuntu0.16.04.16+esm1USN-5006-2

libapache2-mod-php7.2Ubuntu

Fixed in:7.2.24-0ubuntu0.18.04.8USN-5006-1

libapache2-mod-php7.4Ubuntu

Fixed in:7.4.3-4ubuntu2.5USN-5006-1

php5Ubuntu

Fixed in:5.5.9+dfsg-1ubuntu4.29+esm14USN-5006-2

php5-cgiUbuntu

Fixed in:5.5.9+dfsg-1ubuntu4.29+esm14USN-5006-2

php5-cliUbuntu

Fixed in:5.5.9+dfsg-1ubuntu4.29+esm14USN-5006-2

php5-fpmUbuntu

Fixed in:5.5.9+dfsg-1ubuntu4.29+esm14USN-5006-2

php7.0Ubuntu

Fixed in:7.0.33-0ubuntu0.16.04.16+esm1USN-5006-2

php7.0-cgiUbuntu

Fixed in:7.0.33-0ubuntu0.16.04.16+esm1USN-5006-2

php7.0-cliUbuntu

Fixed in:7.0.33-0ubuntu0.16.04.16+esm1USN-5006-2

php7.0-fpmUbuntu

Fixed in:7.0.33-0ubuntu0.16.04.16+esm1USN-5006-2

php7.2Ubuntu

Fixed in:7.2.24-0ubuntu0.18.04.8USN-5006-1

php7.2-cgiUbuntu

Fixed in:7.2.24-0ubuntu0.18.04.8USN-5006-1

php7.2-cliUbuntu

Fixed in:7.2.24-0ubuntu0.18.04.8USN-5006-1

php7.2-fpmUbuntu

Fixed in:7.2.24-0ubuntu0.18.04.8USN-5006-1

php7.4Ubuntu

Fixed in:7.4.3-4ubuntu2.5USN-5006-1

php7.4-cgiUbuntu

Fixed in:7.4.3-4ubuntu2.5USN-5006-1

php7.4-cliUbuntu

Fixed in:7.4.3-4ubuntu2.5USN-5006-1

php7.4-fpmUbuntu

Fixed in:7.4.3-4ubuntu2.5USN-5006-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityLow

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

Exploit Intelligence

1.72%probability of exploitation in 30 days

75thpercentile

Elevated risk: more likely to be exploited than 75% of all known CVEs.

References

Patch4

Third-Party Advisory2

Related Vulnerabilities

Other CWE-125 (Out-of-bounds Read) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2014-0160	High	7.5	100%	KEV	Fix
CVE-2025-5777	High	7.5	100%	KEV + Ransom	Fix
CVE-2021-4034	High	7.8	95%	KEV	Fix
CVE-2023-21769	High	7.5	92%	-	Fix
CVE-2023-49285	High	8.6	89%	-	Fix
CVE-2020-8794	Critical	9.8	89%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.