CVE-2024-20253

RCE in Cisco Unified Communications Manager ≤ 12.5\(1\)su8

RCE Deserialization

Published

26 January 2024

Modified

17 June 2026

Patch / advisory

View advisory

CVSS Score v3.1 9.9

Click a component to see what it means

Raw vector

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

EPSS Score 0.024 84th percentile

Risk Priority 74 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2024-20253 is a critical-severity Deserialization of Untrusted Data (CWE-502) vulnerability in Cisco Unified Communications Manager. Its CVSS base score is 9.9 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Junk Data (T1001.001); ranked in the top 16% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2024-17968

Vulnerability Data

A vulnerability in multiple Cisco Unified Communications and Contact Center Solutions products could allow an unauthenticated, remote attacker to execute arbitrary code on an affected device. This vulnerability is due to the improper processing of user-provided data that is being…

read into memory. An attacker could exploit this vulnerability by sending a crafted message to a listening port of an affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying operating system with the privileges of the web services user. With access to the underlying operating system, the attacker could also establish root access on the affected device.

CWE(s): CWE-502 NVD-CWE-noinfo

Related Threats

MITRE ATT&CK Enterprise Techniques

T1001.001 Junk Data Command And Control

Adversaries may add junk data to protocols used for command and control to make detection more difficult.

attack.mitre.org →

T1001.003 Protocol or Service Impersonation Command And Control

Adversaries may impersonate legitimate protocols or web service traffic to disguise command and control activity and thwart analysis efforts.

attack.mitre.org →

T1003.001 LSASS Memory Credential Access

Adversaries may attempt to access credential material stored in the process memory of the Local Security Authority Subsystem Service (LSASS).

attack.mitre.org →

T1003.007 Proc Filesystem Credential Access

Adversaries may gather credentials from the proc filesystem or `/proc`.

attack.mitre.org →

T1005 Data from Local System Collection

Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.

attack.mitre.org →

T1006 Direct Volume Access Stealth

Adversaries may directly access a volume to bypass file access controls and file system monitoring.

attack.mitre.org →

Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

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CVE-2026-20131Same vendor: Cisco

CVE-2018-15381Same vendor: Cisco

CVE-2025-20124Same vendor: Cisco

CVE-2019-15271Same vendor: Cisco

CVE-2019-12630Same vendor: Cisco

CVE-2020-27131Same vendor: Cisco

CVE-2018-0147Same vendor: Cisco

Affected Assets

cisco

unified communications manager

≤ 12.5\(1\)su8 · 14.0 — 14su3 · ≤ 12.5\(1\)su8

cisco

unified communications manager im and presence service

≤ 12.5\(1\)su8 · 14.0 — 14.0su3

cisco

unity connection

≤ 12.5\(1\)su8 · 14.0 — 14su3

cisco

unified contact center express

12.5\(1\)

cisco

virtualized voice browser

12.5\(1\), 12.6\(1\), 12.6\(2\)

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can uncover deserialization flaws before deployment.

SI-10 Information Input Validation good match

Input validation directly stops deserialization of untrusted data by ensuring inputs are valid before processing.

SA-8 Security and Privacy Engineering Principles partial match

Engineering principles such as safe deserialization and input sanitization structurally prevent the weakness from being introduced.

SI-7 Software, Firmware, and Information Integrity partial match

Integrity verification tools can detect malformed or tampered serialized data after the fact.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-02 none match

blocks

PR.PS-02 addresses only post-deployment updates/patching and cannot prevent introduction of unsafe deserialization code, yet it can remediate some instances when the flaw exists in outdated libraries or components.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match

removes

A.5.15 Access control partial match

removes

A.5.16 Identity management partial match

removes

A.5.17 Authentication information partial match

removes

A.5.18 Access rights partial match

removes

A.8.10 Information deletion partial match

removes