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
“—” beside the score: it is equal to NVD's CVSS score.
This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 9.1% (95th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
Also known asEUVD-2026-16068 (ENISA EUVD)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5HIGHmedium confidence
- EG Risk
- 65EG Risk 65/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity75% × 45%Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation40% × 40%EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.Automatability100% × 15%CISA's SSVC Automatable value: yes (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 9.1%
- EPSS %ILE
- 95th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
- EG Likelihood
- 9.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-30). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
March 26, 2026
Last Modified
July 15, 2026
Advisory Details (10)
Auto-updated Jul 3, 2026Affected: 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-2026:20580Affected: 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-2026:20565Affected: 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-2026:20564Affected: Red Hat Enterprise Linux 10.0 Extended Update Support.
https://access.redhat.com/errata/RHSA-2026:11901Affected: Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions.
https://access.redhat.com/errata/RHSA-2026:10257Affected: Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions.
https://access.redhat.com/errata/RHSA-2026:10256Affected: Red Hat Enterprise Linux 9.4 Extended Update Support.
https://access.redhat.com/errata/RHSA-2026:10255oss-security - [ADVISORY] SQUID-2026:1 Denial of Service in ICP Request handling (CVE-2026-33526)
http://www.openwall.com/lists/oss-security/2026/03/25/2SQUID-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-gvwgcommit 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(13)
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-2026:20564Red Hat Product SecurityHigh
Red Hat Security Advisory: squid:4 security update
- RHSA-2026:20580Red Hat Product SecurityHigh
Red Hat Security Advisory: squid:4 security update
- 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
- +5 more
Patch Availability(14)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | squidclient (3.5.12-1ubuntu7.16+esm7) @ xenial | 2026-10-24 | ubuntu |
| ubuntu | squidclient (5.9-0ubuntu0.22.04.5) @ jammy | 2026-10-24 | ubuntu |
| redhat | squid:4-8040020260514123440.522a0ee4 | 2026-05-26 | redhat |
| redhat | squid:4-8080020260514105733.63b34585 | 2026-05-26 | redhat |
| redhat | squid:4-8060020260518090356.ad008a3a | 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.
Affected Packages
(4 across 4 ecosystems)
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| squid | 4.13-10 ... 4.13-10+deb11u6 (7 versions) |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| squid | 5.7-2 ... 5.7-2+deb12u5 (6 versions) |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| squid | 6.13-2, 6.13-2+deb13u1 |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| squid | 6.13-2, 7.1-1, 7.2-1, 7.2-2, 7.4-1 |
| — |
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 8× in last 7d / 40× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 96 of 156 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 4 repeat rows among the latest 100 are merged into the row they repeat. The 60 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-10-31 16:32 UTCEPSS rescoreEPSS 9.1% · 95th percentile
- 2026-10-31 13:52 UTCEG score recompute
- 2026-10-31 13:52 UTCVendor advisory
- 2026-10-30 16:34 UTCEPSS rescoreEPSS 9.1% · 95th percentile
- 2026-10-29 16:33 UTCEPSS rescoreEPSS 9.1% · 95th percentile
- 2026-10-28 16:32 UTCEPSS rescoreEPSS 9.1% · 95th percentile
- 2026-10-27 16:31 UTCEPSS rescoreEPSS 9.1% · 95th percentile
- 2026-10-26 16:31 UTCEPSS rescoreEPSS 9.1% · 95th percentile
- 2026-10-25 16:32 UTCEPSS rescoreEPSS 9.1% · 95th percentile
- 2026-10-25 14:34 UTCEG score recompute
- 2026-10-24 16:32 UTCEPSS rescoreEPSS 9.1% · 95th percentile
- 2026-10-24 14:47 UTCEG score recompute
- 2026-10-24 14:47 UTCVendor advisory
- 2026-10-23 16:31 UTCEPSS rescoreEPSS 9.1% · 95th percentile
- 2026-10-22 16:34 UTCEPSS rescoreEPSS 8.9% · 95th percentile
- 2026-10-21 16:32 UTCEPSS rescoreEPSS 8.9% · 95th percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 8.9% · 95th percentile
- 2026-10-19 16:31 UTCEPSS rescoreEPSS 8.9% · 95th percentile
- 2026-10-18 03:46 UTCEG score recompute
- 2026-10-17 16:34 UTCEPSS rescoreEPSS 8.9% · 95th percentile
- 2026-10-17 15:44 UTCEG score recompute
- 2026-10-17 15:44 UTCVendor advisory
- 2026-10-16 16:41 UTCEPSS rescoreEPSS 8.9% · 95th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 8.9% · 95th percentile
- 2026-10-14 16:32 UTCEPSS rescoreEPSS 8.9% · 95th percentile
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- 2026-10-13 16:34 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-10-12 16:13 UTCEG score recompute
- 2026-10-11 19:55 UTCEG score recompute
- 2026-10-11 17:09 UTCEG score recompute
- 2026-10-11 14:36 UTCEG score recompute
- 2026-10-11 13:48 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-10-11 05:55 UTCOSV refresh
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-10-08 17:12 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-10-07 23:47 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-10-06 15:17 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-10-05 17:42 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-10-03 14:25 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-10-01 19:49 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-09-28 13:51 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-09-26 15:58 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-09-26 00:26 UTCEPSS rescoreEPSS 13% · 96th percentile
- 2026-09-21 17:49 UTCOSV refresh
- 2026-09-18 19:28 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-17 19:30 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-16 14:08 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-16 05:15 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-15 03:11 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-13 16:47 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-12 15:01 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-11 14:53 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-11 09:37 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-10 09:34 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-08 22:00 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-07 16:01 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-06 13:47 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-04 05:06 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-02 14:11 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-02 14:01 UTCOSV refresh
- 2026-09-01 13:53 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-09-01 04:39 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-30 19:17 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-30 01:22 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-28 21:41 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-27 14:25 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-26 14:46 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-25 13:49 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-24 14:17 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-23 00:19 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-21 23:49 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-20 22:55 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-19 17:03 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-18 13:48 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-17 13:47 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-16 14:56 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-16 10:12 UTCEG score recompute
- 2026-08-16 10:12 UTCVendor advisory
- 2026-08-16 02:14 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-15 01:30 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-14 19:28 UTCVendor advisory
- 2026-08-14 06:29 UTCEG score recompute
- 2026-08-14 06:29 UTCVendor advisory
- 2026-08-13 22:00 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-12 20:46 UTCEG score recompute
- 2026-08-12 20:46 UTCVendor advisory
- 2026-08-12 13:50 UTCEPSS rescoreEPSS 8.9% · 94th percentile
- 2026-08-11 20:52 UTCEG score recompute
- 2026-08-11 20:52 UTCVendor advisory
- 2026-08-11 03:54 UTCVendor advisory
- 2026-08-10 05:39 UTCVendor advisory
- 2026-08-09 17:50 UTCEG score recompute
- 2026-08-09 17:50 UTCVendor advisory
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownDebian:11:squid
- CVE-2005-0194EG 10.0EPSS p92HIGH
- CVE-2004-0541EG 10.0EPSS p99HIGH
- CVE-2020-15049EG 9.9EPSS p93CRITICAL
- CVE-2025-21311EG 9.8CRITICAL
- CVE-2020-11945EG 9.8EPSS p98CRITICAL
- CVE-2019-12519EG 9.8EPSS p94CRITICAL
- CVE-2019-12524EG 9.8EPSS p90CRITICAL
- CVE-2019-12526EG 9.8EPSS p97CRITICAL
- CVE-2019-12525EG 9.8EPSS p98CRITICAL
- CVE-2025-54574EG 9.3EPSS p98CRITICAL
Same vendor
5 shownredhat:RHSA-2026:10255 · ubuntu:USN-8157-1 · ubuntu:USN-8941-1
Frequently asked(5)
What is CVE-2026-33526?
When was the CVE record for CVE-2026-33526 published?
Is CVE-2026-33526 actively exploited?
What is the CVSS score of CVE-2026-33526?
How do I remediate CVE-2026-33526?
Dependency Blast Radius
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