Squid is a caching proxy for the Web. Due to an expired pointer reference bug, Squid prior to version 6.6 is vulnerable to a Denial of Service attack against Cache Manager error responses. This problem allows a trusted client to perform Denial of Service when generating error pages for Client Manager reports. Squid older than 5.0.5 have not been tested and should be assumed to be vulnerable. All Squid-5.x up to and including 5.9 are vulnerable. All Squid-6.x up to and including 6.5 are vulnerable. This bug is fixed by Squid version 6.6. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives. As a workaround, prevent access to Cache Manager using Squid's main access control: http_access deny manager.
CVE-2024-23638
“▲” beside the score: it is higher than NVD's CVSS score.
Score elevated to 7.9 because EPSS predicted 60% probability of exploitation within the next 30 days (99th percentile of EPSS-scored CVEs) when EchelonGraph scored this CVE. NVD baseline CVSS 6.5 retained for reference. Confidence: see factors.
Also known asEUVD-2024-21127 (ENISA EUVD)Source: ENISA EUVD
- High exploitation likelihood — EPSS 60%
- CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
A fix is available — apply it.
- CVSS v3
- 6.5
- EG Score
- 7.9HIGHhigh confidence
- EG Risk
- 55EG Risk 55/100
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)Severity65% × 45%Impact severity (EG Severity): CVSS 6.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation65% × 40%EchelonGraph's fixed weight for EG-KEV Tier 2 (Weaponized): a constant, not a probability.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).Exploitation public PoC (CISA Vulnrichment) · Automatable no (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. - EPSS PROB
- 60%
- EPSS %ILE
- 99th
- 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 (7.9): severity, escalated by confirmed exploitation. This CVE's 7.9 is EPSS's lift toward 9.0 from its impact severity (EG Severity, CVSS 6.5 MEDIUM): a likelihood of exploitation, not impact.
- EG Severity
- 6.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
- EG Likelihood
- 60% 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; Track* at high (mission-essential systems).CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade 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; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation public PoC (CISA Vulnrichment) · Automatable no (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)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (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
January 24, 2024
Last Modified
November 21, 2024
Advisory Details (9)
Auto-updated Oct 30, 2026Implicit Assertion in Stream Handling | Squid-Security-Audit
https://megamansec.github.io/Squid-Security-Audit/stream-assert.html[SECURITY] Fedora 39 Update: squid-6.9-1.fc39 - package-announce - Fedora mailing-lists
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XWQHRDRHDM5PQTU6BHH4C5KGL37X6TVI/[SECURITY] Fedora 38 Update: squid-6.9-1.fc38 - package-announce - Fedora mailing-lists
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/7R4KPSO3MQT3KAOZV7LC2GG3CYMCGK7H/SQUID-2023:11 Denial of Service in Cache Manager · Advisory · squid-cache/squid · GitHub
https://github.com/squid-cache/squid/security/advisories/GHSA-j49p-553x-48rxcommit e8118a738121 (squid-cache/squid)
Fix landed in squid-cache/squid commit e8118a738121 — awaiting tagged release
https://github.com/squid-cache/squid/commit/e8118a7381213f5cfcdeb4cec1d2d854bfd261c8commit 290ae202883a (squid-cache/squid)
Fix landed in squid-cache/squid commit 290ae202883a — awaiting tagged release
https://github.com/squid-cache/squid/commit/290ae202883ac28a48867079c2fb34c40efd382bVendor Advisories for CVE-2024-23638(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Patch Availability(3)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | squidclient (6.1-2ubuntu1.3) @ mantic | 2026-10-30 | ubuntu |
| redhat | squid:4-8100020241113143337.489197e6 | 2024-11-14 | redhat |
| redhat | squid-7:5.5-13.el9_4 | 2024-07-25 | 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+deb11u1, 4.13-10+deb11u2 |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| squid | 5.7-2 |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| squid | — |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| squid | — |
| — |
Weakness Classification(2)
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 6× in last 7d / 33× 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 92 of 153 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. 8 repeat rows among the latest 100 are merged into the row they repeat. The 61 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-10-31 16:30 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-30 19:03 UTCEG score recompute
- 2026-10-30 19:03 UTCVendor advisory
- 2026-10-30 16:31 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-28 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-27 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-25 17:17 UTCEG score recompute
- 2026-10-25 16:30 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-24 16:30 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-24 08:40 UTCEG score recompute
- 2026-10-24 08:40 UTCVendor advisory
- 2026-10-23 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-22 16:31 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-21 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-20 16:30 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-19 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-18 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-18 07:26 UTCEG score recompute
- 2026-10-16 16:36 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-15 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-14 16:30 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-13 16:30 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-12 18:01 UTCEG score recompute
- 2026-10-12 16:31 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-12 04:54 UTCOSV refresh
Show 67 moreShow fewer
- 2026-10-11 21:26 UTCEG score recompute
- 2026-10-11 16:20 UTCEG score recompute
- 2026-10-11 13:45 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-10 19:58 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-09 20:05 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-07 23:46 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-06 15:15 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-03 14:23 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-10-01 19:48 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-30 16:57 UTCEG score recompute
- 2026-09-30 15:01 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-24 14:01 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-23 13:46 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-22 10:15 UTCOSV refresh
- 2026-09-16 14:06 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-16 05:11 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-15 03:08 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-12 14:59 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-11 09:34 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-08 21:58 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-06 13:46 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-05 15:26 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-04 13:58 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-09-03 07:29 UTCOSV refresh
- 2026-09-02 14:10 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-30 19:15 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-30 01:20 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-28 21:39 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-27 14:23 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-26 14:44 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-21 23:47 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-20 22:53 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-19 17:02 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-18 13:46 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-17 13:45 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-16 20:56 UTCOSV refresh
- 2026-08-16 14:54 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-16 02:12 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-15 01:28 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-13 21:58 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-12 13:49 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-11 13:40 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-05 19:15 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-08-01 15:06 UTCOSV refresh
- 2026-07-30 16:26 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-30 01:29 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-28 15:34 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-26 14:53 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-25 14:16 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-24 14:16 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-23 14:17 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-23 02:34 UTCEG score recompute▲ 1.40
- 2026-07-22 23:20 UTCEG score recompute
- 2026-07-22 14:07 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-20 17:06 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-19 02:28 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-18 10:03 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-15 16:56 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-14 21:55 UTCOSV refresh
- 2026-07-13 22:28 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-13 06:11 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-12 05:45 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-11 08:26 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-09 19:09 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-06 16:26 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-05 02:29 UTCEPSS rescoreEPSS 60% · 99th percentile
- 2026-07-01 15:05 UTCEPSS rescoreEPSS 60% · 99th percentile
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
6 shownubuntu:USN-6728-1 · redhat:RHSA-2024:9644 · redhat:RHSA-2024:4861
Frequently asked(5)
What is CVE-2024-23638?
When was the CVE record for CVE-2024-23638 published?
Is CVE-2024-23638 actively exploited?
What is the CVSS score of CVE-2024-23638?
How do I remediate CVE-2024-23638?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2024-23638
Is Your Infrastructure Affected by CVE-2024-23638?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.