Unauthenticated remote access to proxy cache in Apache Traffic Server can be exploited across enterprises, enabling cache poisoning/data tampering in core web infrastructure.
CVE-2026-111811
Unauthenticated network read/write/delete of Apache Traffic Server cache via tsmemcache plugin.
Is CVE-2026-111811 being exploited?
Not confirmed. CVE-2026-111811 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.36% probability of exploitation in the next 30 days.
How severe is CVE-2026-111811?
CVE-2026-111811 is rated Critical with a CVSS score of 9.4. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-111811?
Yes. A fix has been recorded for CVE-2026-111811. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-111811 affect?
CVE-2026-111811 affects Apache Traffic Server tsmemcache plugin, Versions: 8.0.0–8.1.11, Versions: 9.0.0–9.2.15, Versions: 10.0.0–10.1.4, 10.2.0, and 1 further product or version. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-111811?
Upgrade to 9.2.16, 10.1.5, or 10.2.1; disable tsmemcache if unused.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated remote read, write, delete of proxy cache — allows cache poisoning, content tampering, data exfiltration and response manipulation.
Immediate action required
- affected>= 8.0.0 and <= 8.1.11
- affected>= 9.0.0 and <= 9.2.15
- affected>= 10.0.0 and <= 10.1.4
- affected10.2.0
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.