CVE-2024-20451 [High] | Denial of Service in Spa 301 Firmware

Multiple vulnerabilities in the web-based management interface of Cisco Small Business SPA300 Series IP Phones and Cisco Small Business SPA500 Series IP Phones could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly. These vulnerabilities exist because HTTP packets are not properly checked for errors. An attacker could exploit this vulnerability by sending a crafted HTTP packet to the remote interface of an affected device. A successful exploit could allow the attacker to cause a DoS condition on the device.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	1.29%	0.75%	-0.54%
2	2026-03-16	1.68%	1.29%	-0.39%
3	2025-11-21	—	1.68%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

1.29%

0.75%

-0.54%

2026-03-16

1.68%

1.29%

-0.39%

2025-11-21

—

1.68%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.5	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	3.6	[email protected]
7.5	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	3.6	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.5

3.1

HIGH

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

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

3.6

[email protected]

7.5

3.1

HIGH

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

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

3.6

[email protected]

Affected software / configurations for CVE-2024-20451

Vendor	Product	Version	Raw CPE
cisco	spa_301_firmware	—	cpe:2.3:o:cisco:spa_301_firmware::::::::
cisco	spa_303_firmware	—	cpe:2.3:o:cisco:spa_303_firmware::::::::
cisco	spa_501g_firmware	—	cpe:2.3:o:cisco:spa_501g_firmware::::::::
cisco	spa_502g_firmware	—	cpe:2.3:o:cisco:spa_502g_firmware::::::::
cisco	spa_504g_firmware	—	cpe:2.3:o:cisco:spa_504g_firmware::::::::
cisco	spa_508g_firmware	—	cpe:2.3:o:cisco:spa_508g_firmware::::::::
cisco	spa_509g_firmware	—	cpe:2.3:o:cisco:spa_509g_firmware::::::::
cisco	spa_512g_firmware	—	cpe:2.3:o:cisco:spa_512g_firmware::::::::
cisco	spa_514g_firmware	—	cpe:2.3:o:cisco:spa_514g_firmware::::::::
cisco	spa_525g_firmware	—	cpe:2.3:o:cisco:spa_525g_firmware::::::::
cisco	spa_525g2_firmware	—	cpe:2.3:o:cisco:spa_525g2_firmware::::::::

References for CVE-2024-20451

URL	Tags
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-spa-http-vulns-RJZmX2Xz	Vendor Advisory

URL

CVE-2024-20451

Exploit prediction scoring system (EPSS) score for CVE-2024-20451

Common vulnerability scoring system (CVSS) metrics for CVE-2024-20451

Weakness enumeration for CVE-2024-20451

Affected software / configurations for CVE-2024-20451

References for CVE-2024-20451