Is CVE-2016-2403 in the CISA KEV catalog?

No. CVE-2016-2403 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2016-2403?

CVE-2016-2403 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2016-2403?

CVE-2016-2403 has an EPSS score of 2.93% (85th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2016-2403?

Upgrade symfony on debian 11 to 2.8.6+dfsg-1 or later.

CVE & CISA-KEV Catalog

CVE-2016-2403

CRITICALEPSS 85th pctl

9.8

CVSS v3

NVD

Description

Symfony before 2.8.6 and 3.x before 3.0.6 allows remote attackers to bypass authentication by logging in with an empty password and valid username, which triggers an unauthenticated bind.

CWE-287Improper Authentication

How to fix

Remediation Available

symfonyDebian

Fixed in:2.8.6+dfsg-1CVE-2016-2403

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 ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

2.93%probability of exploitation in 30 days

85thpercentile

Elevated risk: more likely to be exploited than 85% of all known CVEs.

References

Vendor Advisory1

symfony.com

Third-Party Advisory1

securityfocus.com

Other references1

debian.org

Related Vulnerabilities

Other CWE-287 (Improper Authentication) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-35082	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2023-35078	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2017-7921	Critical	9.8	100%	KEV	-
CVE-2024-7593	Critical	9.8	100%	KEV	-
CVE-2023-46805	High	8.2	100%	KEV + Ransom	-
CVE-2022-40684	Critical	9.8	100%	KEV + Ransom	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 2026-05-13.