Widely deployed Squid proxy; ICP DoS could disrupt services across many orgs; patch exists.
CVE-2026-33526
DoS in Squid via ICP traffic; heap-use-after-free in <7.5 when ICP enabled.
Is CVE-2026-33526 being exploited?
Not confirmed. CVE-2026-33526 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 8.9% probability of exploitation in the next 30 days.
How severe is CVE-2026-33526?
CVE-2026-33526 is rated Critical with a CVSS score of 9.2. 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-2026-33526?
Yes. A fix has been recorded for CVE-2026-33526. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-33526 affect?
CVE-2026-33526 affects Squid < 7.5. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-33526?
Upgrade to 7.5+; disable ICP if not needed; verify patch.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote attacker can crash/deny service by triggering heap UAF in ICP processing; requires ICP port enabled.
Patch when possible
- affected< 7.5
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.