# CVE-2026-76490: Cisco Expressway Series out-of-bounds write and code injection flaws

Source: https://junglewise.ai/threats/cve-2026-76490-as-part-of-cisco-s-ongoing-commitment-to-proactive-security-and  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-21. Updated: 2026-10-21  
License: CC BY 4.0 with a link back

CVE-2026-76490 · Severity: high · CVSS 8.6 · Published 2026-10-21

Cisco Expressway Series, a video conferencing and collaboration platform used by enterprises, contains multiple memory corruption and code injection vulnerabilities discovered during internal security review. An attacker on the network can exploit these flaws to cause denial of service or potentially execute arbitrary code without authentication. The issues were discovered internally and are not currently known to be exploited in the wild.

Technologies: [Cisco Expressway-C](https://junglewise.ai/threats/technologies/expressway-c), [Cisco Expressway-E](https://junglewise.ai/threats/technologies/expressway-e). Vendors: [Cisco](https://junglewise.ai/threats/vendors/cisco).

## Quick answers

**Is CVE-2026-76490 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-76490 being exploited in the wild.

**How severe is CVE-2026-76490?** High severity, with a CVSS score of 8.6, published 21 October 2026.

**Which products and versions are affected?** Cisco Expressway-C X14 and earlier, X15.5.3 and earlier; Cisco Expressway-E X14 and earlier, X15.5.3 and earlier.

**Is there a fix for CVE-2026-76490?** Yes: fixed in Expressway-C and Expressway-E: X15.5.20 for X15 branch; later versions for X14 require migration to fixed release. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-76490 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-76490?** Check whether you run Cisco Expressway-C or Cisco Expressway-E at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Expressway-C and Expressway-E: X15.5.20 for X15 branch; later versions for X14 require migration to fixed release

## Technical details

The advisory groups eight vulnerabilities across multiple weakness categories including out-of-bounds writes (CWE-787), null pointer dereferences (CWE-476), code injection (CWE-94), and improper permission assignment (CWE-732). All vulnerabilities are network-accessible and require no authentication or user interaction. Exploitation could result in denial of service or code execution on Expressway-C and Expressway-E appliances.

## Affected products

- Cisco Expressway-C X14 and earlier, X15.5.3 and earlier
- Cisco Expressway-E X14 and earlier, X15.5.3 and earlier

## Timeline

- 2026-10-21: disclosed

## References

- [https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-exwy-hardening-FhcqBVcs](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-exwy-hardening-FhcqBVcs)

## Related threats

- [Cisco Expressway Series insecure temporary files](https://junglewise.ai/threats/cve-2026-76497-as-part-of-cisco-s-ongoing-commitment-to-proactive-security-and)
- [Cisco Expressway Series improper link resolution](https://junglewise.ai/threats/cve-2026-76496-as-part-of-cisco-s-ongoing-commitment-to-proactive-security-and)
- [Cisco Expressway Series incorrect permission assignment](https://junglewise.ai/threats/cve-2026-76495-as-part-of-cisco-s-ongoing-commitment-to-proactive-security-and)
- [Cisco Expressway Series code injection](https://junglewise.ai/threats/cve-2026-76494-as-part-of-cisco-s-ongoing-commitment-to-proactive-security-and)
- [Cisco Expressway Series uncaught exceptions denial of service](https://junglewise.ai/threats/cve-2026-76493-as-part-of-cisco-s-ongoing-commitment-to-proactive-security-and)