How severe is CVE-2021-1495?

CVE-2021-1495 has a CVSS 3.x base score of 5.8, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2021-1495 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-1495?

CVE-2021-1495 primarily affects Cisco Firepower Threat Defense. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-1495?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-1495 published?

CVE-2021-1495 was published on 2021-04-29 and last updated on 2026-06-17.

CVE-2021-1495

CVE-2021-1495 is a medium-severity vulnerability in Cisco Firepower Threat Defense with a CVSS 3.x base score of 5.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-755.

Key facts

Severity: Medium (CVSS 3.x base score 5.8)
CVSS v2: 5.0
EPSS exploit prediction: 2% (75th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-755
Affected product: Cisco Firepower Threat Defense
Published: 2021-04-29
Last modified: 2026-06-17

Description

Multiple Cisco products are affected by a vulnerability in the Snort detection engine that could allow an unauthenticated, remote attacker to bypass a configured file policy for HTTP. The vulnerability is due to incorrect handling of specific HTTP header parameters. An attacker could exploit this vulnerability by sending crafted HTTP packets through an affected device. A successful exploit could allow the attacker to bypass a configured file policy for HTTP packets and deliver a malicious payload.

Frequently asked questions

What is CVE-2021-1495?: Multiple Cisco products are affected by a vulnerability in the Snort detection engine that could allow an unauthenticated, remote attacker to bypass a configured file policy for HTTP. The vulnerability is due to incorrect handling of specific HTTP header parameters. An attacker could exploit this vulnerability by sending crafted HTTP packets through an affected device. A successful exploit could allow the attacker to bypass a configured file policy for HTTP packets and deliver a malicious payload.
How severe is CVE-2021-1495?: CVE-2021-1495 has a CVSS 3.x base score of 5.8, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-1495 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-1495?: CVE-2021-1495 primarily affects Cisco Firepower Threat Defense. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-1495?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-1495 published?: CVE-2021-1495 was published on 2021-04-29 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
cpe:2.3:a:cisco:ios_xe:*:*:*:*:*:*:*:*
cpe:2.3:a:snort:snort:*:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:*:*:*:*:*:*:*:*

More vulnerabilities in Cisco Firepower Threat Defense

CVE-2021-44228 — Critical (CVSS 10.0): Apache Log4j2 2.0-beta9 through 2.15.0 (excluding security releases 2.12.2, 2.12.3, and 2.3.1) JNDI features used in…
CVE-2018-0101 — Critical (CVSS 10.0): A vulnerability in the Secure Sockets Layer (SSL) VPN functionality of the Cisco Adaptive Security Appliance (ASA)…
CVE-2025-20333 — Critical (CVSS 9.9): A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco…
CVE-2024-20412 — Critical (CVSS 9.3): A vulnerability in Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 1000, 2100, 3100, and 4200 Series…
CVE-2020-3187 — Critical (CVSS 9.1): A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower…
CVE-2025-20363 — Critical (CVSS 9.0): A vulnerability in the web services of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco Secure…

All CVEs affecting Cisco Firepower Threat Defense →

Other CWE-755 (Improper Handling of Exceptional Conditions) vulnerabilities

CVE-2025-34193 — Critical (CVSS 9.8): Vasion Print (formerly PrinterLogic) Virtual Appliance Host versions prior to 25.1.102 and Application versions prior…
CVE-2025-10156 — Critical (CVSS 9.8): An Improper Handling of Exceptional Conditions vulnerability in the ZIP archive scanning component of mmaitre314…
CVE-2021-42142 — Critical (CVSS 9.8): An issue was discovered in Contiki-NG tinyDTLS through master branch 53a0d97. DTLS servers mishandle the early use of a…
CVE-2021-42141 — Critical (CVSS 9.8): An issue was discovered in Contiki-NG tinyDTLS through 2018-08-30. One incorrect handshake could complete with…
CVE-2023-38406 — Critical (CVSS 9.8): bgpd/bgp_flowspec.c in FRRouting (FRR) before 8.4.3 mishandles an nlri length of zero, aka a "flowspec overflow."
CVE-2022-23121 — Critical (CVSS 9.8): This vulnerability allows remote attackers to execute arbitrary code on affected installations of Netatalk.…

Browse all CWE-755 (Improper Handling of Exceptional Conditions) vulnerabilities →