CVE-2024-23638
MediumPublic exploitDue 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.
Published Jan 24, 2024 · Updated Sep 29, 2026 · Also known as DEBIAN-CVE-2024-23638, GHSA-j49p-553x-48rx, ROOT-OS-ALPINE-318-CVE-2024-23638, UBUNTU-CVE-2024-23638
Key Facts
Patch immediately- CVE-2024-23638 is a medium-severity vulnerability (CVSS 6.5 v3.1) affecting Squid (Squid-Cache), rootio-squid, squid3 (ubuntu) and 5 more products.
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 60% probability of exploitation in the next 30 days.
- Fixed versions are available, including libecap 1.0.1-2.module_el8.6.0+2741+01592ae8, libecap 1.0.1-2.module+el8.9.0+1437+df5ea8f0, libecap 1.0.1-2.module+el8.9.0+90083+f7556140.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
6.5
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS (30-day exploit likelihood)
60%
Higher than 99.1% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2024-23638 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
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.
Affected Products
79 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| SquidSquid-Cache | >= < 6.6 | 5.9 |
| rootio-squidrootio | See advisory | 5.9-r00071 |
| squid3ubuntu | See advisory | n/a |
| libecapalma | See advisory | 1.0.1-2.module_el8.6.0+2741+01592ae8 |
| squid-migration-scriptamazon | See advisory | 7:3.5.20-17.amzn2.7.17 |
Patched Releases
libecap
1.0.1-2.module_el8.6.0+2741+01592ae8, 1.0.1-2.module+el8.9.0+1437+df5ea8f0, 1.0.1-2.module+el8.9.0+90083+f7556140
libecap-devel
1.0.1-2.module+el8.9.0+90083+f7556140
rootio-squid
5.9-r00071, 5.9-r00072, 5.9-r00073, 5.9-r00074, 5.9-r00075
Squid
4.10-1ubuntu1.10, 4.13-10+deb11u3, 4.17-150000.5.49.1, 4.17-4.41.1, 5.7-0ubuntu0.22.04.4, 5.7-150400.3.23.1, 5.7-2+deb12u1, 5.9-5.ph3, 5.9-r00071, 5.9-r00072, 5.9-r00073, 5.9-r00074, 5.9-r00075, 6.6-1, 6.6-2.1, 7:3.5.20-17.amzn2.7.17, 7:4.15-10.module_el8.10.0+3916+ed00a4a0.3, 7:4.15-10.module+el8.10.0+1758+80ba9f4b, 7:4.15-10.module+el8.10.0+90442+8ef3f586.3, 7:5.5-13.el9_4, 7:6.6-1.amzn2023.0.3, <=5.9
squid-migration-script
7:3.5.20-17.amzn2.7.17
squid-sysvinit
7:3.5.20-17.amzn2.7.17
squid:4
8100020241113143337.489197e6
Timeline
Publicly disclosed
Jan 24, 2024
Last updated
Sep 29, 2026
Weakness Type
- CWE-672 Operation on a Resource after Expiration or Release
- CWE-825 Expired Pointer Dereference
References
- advisoryRHSA-2024:4861
- advisoryRHSA-2024:9644
- advisoryhttps://bugzilla.suse.com/1217654
- advisoryhttps://bugzilla.suse.com/1219131
- advisoryhttps://github.com/CVEProject/cvelistV5/tree/main/cves/2024/23xxx/CVE-2024-23638.json
FAQ
Common Questions.
Squid is a caching proxy for the Web.
Affected: Squid (Squid-Cache) versions >= < 6.6; rootio-squid; squid3 (ubuntu), among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including libecap 1.0.1-2.module_el8.6.0+2741+01592ae8, libecap 1.0.1-2.module+el8.9.0+1437+df5ea8f0, libecap 1.0.1-2.module+el8.9.0+90083+f7556140.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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