CVE-2024-23638

HIGHNVD 6.57.9
EchelonGraph scoreHIGH confidence

“▲” 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.

Triggered by: EPSS exploit prediction (continuous uplift above 30%)
Sources: EPSS, NVD CVSS v3
Trending — 3 sources updated this weekWeaponized

Also known asEUVD-2024-21127 (ENISA EUVD)Source: ENISA EUVD

7.9EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High exploitation likelihood — EPSS 60%
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 60%CVSS: 6.5Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
6.5
EG Score
7.9HIGHhigh confidence
EG Risk
55
EG 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, 2026
Patch available. Sources: github_commit, github.
Web page

Implicit Assertion in Stream Handling | Squid-Security-Audit

https://megamansec.github.io/Squid-Security-Audit/stream-assert.html
Web page

[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/
Web page

[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/
GitHub advisoryMentions a patch (unverified)

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-48rx
GitHub commit

commit e8118a738121 (squid-cache/squid)

Fix landed in squid-cache/squid commit e8118a738121 — awaiting tagged release

https://github.com/squid-cache/squid/commit/e8118a7381213f5cfcdeb4cec1d2d854bfd261c8
GitHub commit

commit 290ae202883a (squid-cache/squid)

Fix landed in squid-cache/squid commit 290ae202883a — awaiting tagged release

https://github.com/squid-cache/squid/commit/290ae202883ac28a48867079c2fb34c40efd382b

Vendor 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 / EcosystemFix (by version range) / PatchReleasedSource
ubuntusquidclient (6.1-2ubuntu1.3) @ mantic2026-10-30ubuntu
redhatsquid:4-8100020241113143337.489197e62024-11-14redhat
redhatsquid-7:5.5-13.el9_42024-07-25redhat

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)
PackageVulnerable rangeFix by version rangeDependents
squid4.13-10, 4.13-10+deb11u1, 4.13-10+deb11u2
  • every version up to 4.13-10+deb11u3: fixed in 4.13-10+deb11u3
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
squid5.7-2
  • every version up to 5.7-2+deb12u1: fixed in 5.7-2+deb12u1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
squid—
  • every version up to 6.6-1: fixed in 6.6-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
squid—
  • every version up to 6.6-1: fixed in 6.6-1
—

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.

  1. 2026-10-31 16:30 UTCEPSS rescoreEPSS 60% · 99th percentile
  2. 2026-10-30 19:03 UTCEG score recompute
  3. 2026-10-30 19:03 UTCVendor advisory
  4. 2026-10-30 16:31 UTCEPSS rescoreEPSS 60% · 99th percentile
  5. 2026-10-28 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
  6. 2026-10-27 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
  7. 2026-10-25 17:17 UTCEG score recompute
  8. 2026-10-25 16:30 UTCEPSS rescoreEPSS 60% · 99th percentile
  9. 2026-10-24 16:30 UTCEPSS rescoreEPSS 60% · 99th percentile
  10. 2026-10-24 08:40 UTCEG score recompute
  11. 2026-10-24 08:40 UTCVendor advisory
  12. 2026-10-23 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
  13. 2026-10-22 16:31 UTCEPSS rescoreEPSS 60% · 99th percentile
  14. 2026-10-21 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
  15. 2026-10-20 16:30 UTCEPSS rescoreEPSS 60% · 99th percentile
  16. 2026-10-19 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
  17. 2026-10-18 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
  18. 2026-10-18 07:26 UTCEG score recompute
  19. 2026-10-16 16:36 UTCEPSS rescoreEPSS 60% · 99th percentile
  20. 2026-10-15 16:29 UTCEPSS rescoreEPSS 60% · 99th percentile
  21. 2026-10-14 16:30 UTCEPSS rescoreEPSS 60% · 99th percentile
  22. 2026-10-13 16:30 UTCEPSS rescoreEPSS 60% · 99th percentile
  23. 2026-10-12 18:01 UTCEG score recompute
  24. 2026-10-12 16:31 UTCEPSS rescoreEPSS 60% · 99th percentile
  25. 2026-10-12 04:54 UTCOSV refresh
Show 67 more
  1. 2026-10-11 21:26 UTCEG score recompute
  2. 2026-10-11 16:20 UTCEG score recompute
  3. 2026-10-11 13:45 UTCEPSS rescoreEPSS 60% · 99th percentile
  4. 2026-10-10 19:58 UTCEPSS rescoreEPSS 60% · 99th percentile
  5. 2026-10-09 20:05 UTCEPSS rescoreEPSS 60% · 99th percentile
  6. 2026-10-07 23:46 UTCEPSS rescoreEPSS 60% · 99th percentile
  7. 2026-10-06 15:15 UTCEPSS rescoreEPSS 60% · 99th percentile
  8. 2026-10-03 14:23 UTCEPSS rescoreEPSS 60% · 99th percentile
  9. 2026-10-01 19:48 UTCEPSS rescoreEPSS 60% · 99th percentile
  10. 2026-09-30 16:57 UTCEG score recompute
  11. 2026-09-30 15:01 UTCEPSS rescoreEPSS 60% · 99th percentile
  12. 2026-09-24 14:01 UTCEPSS rescoreEPSS 60% · 99th percentile
  13. 2026-09-23 13:46 UTCEPSS rescoreEPSS 60% · 99th percentile
  14. 2026-09-22 10:15 UTCOSV refresh
  15. 2026-09-16 14:06 UTCEPSS rescoreEPSS 60% · 99th percentile
  16. 2026-09-16 05:11 UTCEPSS rescoreEPSS 60% · 99th percentile
  17. 2026-09-15 03:08 UTCEPSS rescoreEPSS 60% · 99th percentile
  18. 2026-09-12 14:59 UTCEPSS rescoreEPSS 60% · 99th percentile
  19. 2026-09-11 09:34 UTCEPSS rescoreEPSS 60% · 99th percentile
  20. 2026-09-08 21:58 UTCEPSS rescoreEPSS 60% · 99th percentile
  21. 2026-09-06 13:46 UTCEPSS rescoreEPSS 60% · 99th percentile
  22. 2026-09-05 15:26 UTCEPSS rescoreEPSS 60% · 99th percentile
  23. 2026-09-04 13:58 UTCEPSS rescoreEPSS 60% · 99th percentile
  24. 2026-09-03 07:29 UTCOSV refresh
  25. 2026-09-02 14:10 UTCEPSS rescoreEPSS 60% · 99th percentile
  26. 2026-08-30 19:15 UTCEPSS rescoreEPSS 60% · 99th percentile
  27. 2026-08-30 01:20 UTCEPSS rescoreEPSS 60% · 99th percentile
  28. 2026-08-28 21:39 UTCEPSS rescoreEPSS 60% · 99th percentile
  29. 2026-08-27 14:23 UTCEPSS rescoreEPSS 60% · 99th percentile
  30. 2026-08-26 14:44 UTCEPSS rescoreEPSS 60% · 99th percentile
  31. 2026-08-21 23:47 UTCEPSS rescoreEPSS 60% · 99th percentile
  32. 2026-08-20 22:53 UTCEPSS rescoreEPSS 60% · 99th percentile
  33. 2026-08-19 17:02 UTCEPSS rescoreEPSS 60% · 99th percentile
  34. 2026-08-18 13:46 UTCEPSS rescoreEPSS 60% · 99th percentile
  35. 2026-08-17 13:45 UTCEPSS rescoreEPSS 60% · 99th percentile
  36. 2026-08-16 20:56 UTCOSV refresh
  37. 2026-08-16 14:54 UTCEPSS rescoreEPSS 60% · 99th percentile
  38. 2026-08-16 02:12 UTCEPSS rescoreEPSS 60% · 99th percentile
  39. 2026-08-15 01:28 UTCEPSS rescoreEPSS 60% · 99th percentile
  40. 2026-08-13 21:58 UTCEPSS rescoreEPSS 60% · 99th percentile
  41. 2026-08-12 13:49 UTCEPSS rescoreEPSS 60% · 99th percentile
  42. 2026-08-11 13:40 UTCEPSS rescoreEPSS 60% · 99th percentile
  43. 2026-08-05 19:15 UTCEPSS rescoreEPSS 60% · 99th percentile
  44. 2026-08-01 15:06 UTCOSV refresh
  45. 2026-07-30 16:26 UTCEPSS rescoreEPSS 60% · 99th percentile
  46. 2026-07-30 01:29 UTCEPSS rescoreEPSS 60% · 99th percentile
  47. 2026-07-28 15:34 UTCEPSS rescoreEPSS 60% · 99th percentile
  48. 2026-07-26 14:53 UTCEPSS rescoreEPSS 60% · 99th percentile
  49. 2026-07-25 14:16 UTCEPSS rescoreEPSS 60% · 99th percentile
  50. 2026-07-24 14:16 UTCEPSS rescoreEPSS 60% · 99th percentile
  51. 2026-07-23 14:17 UTCEPSS rescoreEPSS 60% · 99th percentile
  52. 2026-07-23 02:34 UTCEG score recompute▲ 1.40
  53. 2026-07-22 23:20 UTCEG score recompute
  54. 2026-07-22 14:07 UTCEPSS rescoreEPSS 60% · 99th percentile
  55. 2026-07-20 17:06 UTCEPSS rescoreEPSS 60% · 99th percentile
  56. 2026-07-19 02:28 UTCEPSS rescoreEPSS 60% · 99th percentile
  57. 2026-07-18 10:03 UTCEPSS rescoreEPSS 60% · 99th percentile
  58. 2026-07-15 16:56 UTCEPSS rescoreEPSS 60% · 99th percentile
  59. 2026-07-14 21:55 UTCOSV refresh
  60. 2026-07-13 22:28 UTCEPSS rescoreEPSS 60% · 99th percentile
  61. 2026-07-13 06:11 UTCEPSS rescoreEPSS 60% · 99th percentile
  62. 2026-07-12 05:45 UTCEPSS rescoreEPSS 60% · 99th percentile
  63. 2026-07-11 08:26 UTCEPSS rescoreEPSS 60% · 99th percentile
  64. 2026-07-09 19:09 UTCEPSS rescoreEPSS 60% · 99th percentile
  65. 2026-07-06 16:26 UTCEPSS rescoreEPSS 60% · 99th percentile
  66. 2026-07-05 02:29 UTCEPSS rescoreEPSS 60% · 99th percentile
  67. 2026-07-01 15:05 UTCEPSS rescoreEPSS 60% · 99th percentile

Frequently asked(5)

What is CVE-2024-23638?
CVE-2024-23638 is a high-severity vulnerability; its CVE record was published on January 24, 2024. 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…
When was the CVE record for CVE-2024-23638 published?
The CVE record for CVE-2024-23638 was published on January 24, 2024. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of November 21, 2024; the record at its source may have been updated since.
Is CVE-2024-23638 actively exploited?
CVE-2024-23638 is not currently on CISA's Known Exploited Vulnerabilities catalog. EchelonGraph's EG-KEV model places it in Tier 2 (Weaponized), which is not evidence of exploitation: CISA's SSVC data says a public PoC exists and its EPSS is 50% or more. EchelonGraph does not test whether exploit code works. FIRST EPSS estimates a 60% probability of exploitation in the next 30 days (99th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2024-23638?
CVE-2024-23638 has a CVSS v3 base score of 6.5 (NVD). EchelonGraph synthesises NVD + FIRST EPSS into a combined EG score of 7.9 (HIGH).
How do I remediate CVE-2024-23638?
A fix for CVE-2024-23638 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2024-23638 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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