Security readout for executives and security teams
A malicious or compromised web server could send a specially crafted ESI response that crashes affected Squid proxy/cache servers. The disclosed impact is denial of service, not data theft or remote code execution. Organizations relying on Squid for web access or caching should prioritize upgrades if running affected versions. Exposure is most likely where affected Squid versions process HTTP responses containing Edge Side Includes content from remote servers. Internet egress proxies, caching proxies, or reverse proxy deployments may be affected if they run the vulnerable Squid branches. Distribution packages may include backported fixes, so package advisory status matters. Treat as a service availability risk. Patch during the next security maintenance window, sooner for business-critical proxies or internet-facing reverse proxy roles. There is no cited evidence of active exploitation, but a crashable proxy can disrupt user access and dependent applications. Mitigation focus: Upgrade Squid to 3.5.18 or later, or 4.0.10 or later.; Apply relevant distribution security updates from Ubuntu, Red Hat, Debian, SUSE, Gentoo, or Oracle.; If using vendor packages, verify whether the fix was backported..
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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ATT&CK lookup starting points
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CVE-2016-4556 mapping review
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Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
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CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- GLSA-201607-01CVE reference · vendor-advisory, x_refsource_GENTOO
- RHSA-2016:1140CVE reference · vendor-advisory, x_refsource_REDHAT
- RHSA-2016:1138CVE reference · vendor-advisory, x_refsource_REDHAT
- RHSA-2016:1139CVE reference · vendor-advisory, x_refsource_REDHAT
Products and packages named in the record
CWE details
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