CVE-2019-1635 | Cisco IP Phone 7800 Series and 8800 Series Session Initiation Protocol XML Denial of Service Vulnerability

A vulnerability in the call-handling functionality of Session Initiation Protocol (SIP) Software for Cisco IP Phone 7800 Series and 8800 Series could allow an unauthenticated, remote attacker to cause an affected phone to reload unexpectedly, resulting in a temporary denial of service (DoS) condition. The vulnerability is due to incomplete error handling when XML data within a SIP packet is parsed. An attacker could exploit this vulnerability by sending a SIP packet that contains a malicious XML payload to an affected phone. A successful exploit could allow the attacker to cause the affected phone to reload unexpectedly, resulting in a temporary DoS condition.

Published: 2019-05-03 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2019-1635 is rated Moderate Risk (58.2/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.97%). Mandatory action: Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2019-1635

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.98% 1.97% +0.99%
2 2025-12-12 1.16% 0.98% -0.18%
3 2025-03-30 1.16%

Full EPSS history (11 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2019-1635

CVSS metrics for this CVE.

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 3.0 HIGH
CVSS:3.0/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]
7.8 2.0 HIGH
AV:N/AC:L/Au:N/C:N/I:N/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:C)
Complete availability impact.
10.0 6.9 [email protected]

Weakness enumeration for CVE-2019-1635

Affected software / configurations for CVE-2019-1635

Vendor Product Version Raw CPE
cisco ip_conference_phone_7832_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:ip_conference_phone_7832_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco ip_conference_phone_7832_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:ip_conference_phone_7832_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco ip_conference_phone_7832_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:ip_conference_phone_7832_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco ip_conference_phone_7832_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:ip_conference_phone_7832_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco ip_conference_phone_8832_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:ip_conference_phone_8832_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco ip_conference_phone_8832_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:ip_conference_phone_8832_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco ip_conference_phone_8832_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:ip_conference_phone_8832_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco ip_conference_phone_8832_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:ip_conference_phone_8832_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco ip_phone_7811_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:ip_phone_7811_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco ip_phone_7811_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:ip_phone_7811_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco ip_phone_7811_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:ip_phone_7811_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco ip_phone_7811_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:ip_phone_7811_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco ip_phone_7821_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:ip_phone_7821_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco ip_phone_7821_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:ip_phone_7821_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco ip_phone_7821_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:ip_phone_7821_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco ip_phone_7821_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:ip_phone_7821_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco ip_phone_7841_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:ip_phone_7841_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco ip_phone_7841_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:ip_phone_7841_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco ip_phone_7841_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:ip_phone_7841_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco ip_phone_7841_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:ip_phone_7841_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco ip_phone_7861_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:ip_phone_7861_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco ip_phone_7861_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:ip_phone_7861_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco ip_phone_7861_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:ip_phone_7861_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco ip_phone_7861_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:ip_phone_7861_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco ip_phone_8811_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:ip_phone_8811_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco ip_phone_8811_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:ip_phone_8811_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco ip_phone_8811_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:ip_phone_8811_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco ip_phone_8811_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:ip_phone_8811_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco ip_phone_8841_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:ip_phone_8841_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco ip_phone_8841_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:ip_phone_8841_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco ip_phone_8841_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:ip_phone_8841_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco ip_phone_8841_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:ip_phone_8841_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco ip_phone_8845_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:ip_phone_8845_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco ip_phone_8845_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:ip_phone_8845_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco ip_phone_8845_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:ip_phone_8845_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco ip_phone_8845_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:ip_phone_8845_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco ip_phone_8851_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:ip_phone_8851_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco ip_phone_8851_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:ip_phone_8851_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco ip_phone_8851_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:ip_phone_8851_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco ip_phone_8851_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:ip_phone_8851_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco ip_phone_8861_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:ip_phone_8861_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco ip_phone_8861_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:ip_phone_8861_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco ip_phone_8861_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:ip_phone_8861_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco ip_phone_8861_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:ip_phone_8861_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco ip_phone_8865_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:ip_phone_8865_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco ip_phone_8865_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:ip_phone_8865_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco ip_phone_8865_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:ip_phone_8865_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco ip_phone_8865_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:ip_phone_8865_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco unified_ip_8831_conference_phone1_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:unified_ip_8831_conference_phone1_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco unified_ip_8831_conference_phone1_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:unified_ip_8831_conference_phone1_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco unified_ip_8831_conference_phone1_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:unified_ip_8831_conference_phone1_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco unified_ip_8831_conference_phone1_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:unified_ip_8831_conference_phone1_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco unified_ip_8831_conference_phone_for_third-party_call_control2_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:unified_ip_8831_conference_phone_for_third-party_call_control2_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco unified_ip_8831_conference_phone_for_third-party_call_control2_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:unified_ip_8831_conference_phone_for_third-party_call_control2_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco unified_ip_8831_conference_phone_for_third-party_call_control2_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:unified_ip_8831_conference_phone_for_third-party_call_control2_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco unified_ip_8831_conference_phone_for_third-party_call_control2_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:unified_ip_8831_conference_phone_for_third-party_call_control2_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco wireless_ip_phone_8821_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:wireless_ip_phone_8821_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco wireless_ip_phone_8821_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:wireless_ip_phone_8821_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco wireless_ip_phone_8821_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:wireless_ip_phone_8821_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco wireless_ip_phone_8821_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:wireless_ip_phone_8821_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*
cisco wireless_ip_phone_8821-ex_firmware 9.3\(4\)sr3 cpe:2.3:o:cisco:wireless_ip_phone_8821-ex_firmware:9.3\(4\)sr3:*:*:*:*:*:*:*
cisco wireless_ip_phone_8821-ex_firmware 10.3\(1\)sr4b cpe:2.3:o:cisco:wireless_ip_phone_8821-ex_firmware:10.3\(1\)sr4b:*:*:*:*:*:*:*
cisco wireless_ip_phone_8821-ex_firmware 11.0\(4\)sr2 cpe:2.3:o:cisco:wireless_ip_phone_8821-ex_firmware:11.0\(4\)sr2:*:*:*:*:*:*:*
cisco wireless_ip_phone_8821-ex_firmware 12.1\(1\)sr1 cpe:2.3:o:cisco:wireless_ip_phone_8821-ex_firmware:12.1\(1\)sr1:*:*:*:*:*:*:*

References for CVE-2019-1635

cvelogic Threat Intelligence