Squid is a caching proxy for the Web. Prior to version 7.5, due to heap Use-After-Free, Squid is vulnerable to Denial of Service when handling ICP traffic. This problem allows a remote attacker to perform a reliable and repeatable Denial of Service attack against the Squid service using ICP protocol. This attack is limited to Squid deployments that explicitly enable ICP support (i.e. configure non-zero icp_port). This problem _cannot_ be mitigated by denying ICP queries using icp_access rules. Version 7.5 contains a patch.
CVE-2026-33526
HIGHNVD 7.57.5
EchelonGraph scoreLOW confidence
This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: nvd
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 9%CVSS: 7.5Exploit: NoneExposed: 0
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5(low)
- EPSS
- 94.6%
- KEV
- Not listed
Published
March 26, 2026
Last Modified
June 30, 2026
Advisory Details (10)
Auto-updated Jul 3, 2026Patch available. Sources: github_commit, github, redhat.
redhat Patch Available
Affected: Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions and Red Hat Enterprise Linux 8.8 Telecommunications Update Serv
https://access.redhat.com/errata/RHSA-2026:20580redhat Patch Available
Affected: Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support, Red Hat Enterprise Linux 8.6 Update Services for SAP So
https://access.redhat.com/errata/RHSA-2026:20565redhat Patch Available
Affected: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support and Red Hat Enterprise Linux 8.4 Extended Update Support
https://access.redhat.com/errata/RHSA-2026:20564redhat Patch Available
Affected: Red Hat Enterprise Linux 10.0 Extended Update Support.
https://access.redhat.com/errata/RHSA-2026:11901redhat Patch Available
Affected: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions.
https://access.redhat.com/errata/RHSA-2026:10257redhat Patch Available
Affected: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions.
https://access.redhat.com/errata/RHSA-2026:10256redhat Patch Available
Affected: Red Hat Enterprise Linux 9.4 Extended Update Support.
https://access.redhat.com/errata/RHSA-2026:10255generic Patch Available
oss-security - [ADVISORY] SQUID-2026:1 Denial of Service in ICP Request handling (CVE-2026-33526)
http://www.openwall.com/lists/oss-security/2026/03/25/2github Patch Available
SQUID-2026:1 Denial of Service in ICP Request handling · Advisory · squid-cache/squid · GitHub
https://github.com/squid-cache/squid/security/advisories/GHSA-hpfx-h48q-gvwggithub_commit
commit 8a7d42f9d44b (squid-cache/squid)
Fix landed in squid-cache/squid commit 8a7d42f9d44b — awaiting tagged release
https://github.com/squid-cache/squid/commit/8a7d42f9d44befb8fcbbb619505587c8de6a1e91Vendor Advisories for CVE-2026-33526(11)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- CVE-2026-33526Microsoft Security Response Center (MSRC)High
Squid vulnerable to Denial of Service in ICP Request handling
- RHSA-2026:20565Red Hat Product SecurityHigh
Red Hat Security Advisory: squid:4 security update
- RHSA-2026:11901Red Hat Product SecurityHigh
Red Hat Security Advisory: squid security update
- RHSA-2026:10255Red Hat Product SecurityHigh
Red Hat Security Advisory: squid security update
- RHSA-2026:10256Red Hat Product SecurityHigh
Red Hat Security Advisory: squid security update
- RHSA-2026:10257Red Hat Product SecurityHigh
Red Hat Security Advisory: squid security update
- RHSA-2026:9220Red Hat Product SecurityHigh
Red Hat Security Advisory: squid security update
- RHSA-2026:8880Red Hat Product SecurityHigh
Red Hat Security Advisory: squid security update
- +3 more
Patch Availability(12)
| Vendor / Ecosystem | Fixed in / Patch | Released | Source |
|---|---|---|---|
| redhat | squid:4-8060020260518090356.ad008a3a | 2026-05-26 | redhat |
| redhat | squid:4-8040020260514123440.522a0ee4 | 2026-05-26 | redhat |
| redhat | squid:4-8080020260514105733.63b34585 | 2026-05-26 | redhat |
| redhat | squid-7:6.10-5.el10_0.2 | 2026-04-29 | redhat |
| redhat | squid-7:5.5-13.el9_4.5 | 2026-04-24 | redhat |
| redhat | squid-7:5.2-1.el9_0.10 | 2026-04-23 | redhat |
| redhat | squid-7:5.5-5.el9_2.11 | 2026-04-23 | redhat |
| redhat | squid-7:5.5-19.el9_6.3 | 2026-04-21 | redhat |
| redhat | squid-7:3.5.20-17.el7_9.16 | 2026-04-20 | redhat |
| redhat | squid:4-8100020260408092701.489197e6 | 2026-04-15 | redhat |
| redhat | squid-7:6.10-6.el10_1.3 | 2026-04-14 | redhat |
| redhat | squid-7:5.5-22.el9_7.4 | 2026-03-31 | redhat |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Weakness Classification(3)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Additional Vendor Advisories
(2)
Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.
Data Freshness Timeline
(refreshed 7× in last 7d / 13× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-11 08:27 UTCEPSS rescore
- 2026-07-09 19:10 UTCEPSS rescore
- 2026-07-08 15:15 UTCEPSS rescore
- 2026-07-07 13:46 UTCEPSS rescore
- 2026-07-06 16:27 UTCEPSS rescore
- 2026-07-06 16:27 UTCEPSS rescore
- 2026-07-05 02:30 UTCEPSS rescore
- 2026-07-04 06:31 UTCEPSS rescore
- 2026-07-01 15:06 UTCEPSS rescore
- 2026-06-30 23:22 UTCEPSS rescore
- 2026-06-30 04:32 UTCEG score recompute
- 2026-06-30 04:32 UTCVendor advisory
- 2026-06-30 04:32 UTCNVD updatefirst tracked
Frequently asked(5)
What is CVE-2026-33526?
CVE-2026-33526 is a high vulnerability published on March 26, 2026. Squid is a caching proxy for the Web. Prior to version 7.5, due to heap Use-After-Free, Squid is vulnerable to Denial of Service when handling ICP traffic. This problem allows a remote attacker to perform a reliable and repeatable Denial of Service attack against the Squid service using ICP…
When was CVE-2026-33526 disclosed?
CVE-2026-33526 was first published in the National Vulnerability Database on March 26, 2026, with the most recent update on June 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-33526 actively exploited?
CVE-2026-33526 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 94.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-33526?
CVE-2026-33526 has a CVSS v3 base score of 7.5 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-33526?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-33526, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-33526
Is Your Infrastructure Affected by CVE-2026-33526?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.