squid: Incorrect pointer handling when processing ESI responses allows denial of service
Published May 16, 2018
5.9
MEDIUMCVSS 3.0
EPSS 8.31%
Description
This vulnerability allows remote attackers to deny service on vulnerable installations of The Squid Software Foundation Squid 3.5.27-20180318. Authentication is not required to exploit this vulnerability. The specific flaw exists within ClientRequestContext::sslBumpAccessCheck(). A crafted request can trigger the dereference of a null pointer. An attacker can leverage this vulnerability to create a denial-of-service condition to users of the system. Was ZDI-CAN-6088.
Affected products
-
- Version 3.5.27-20180318StatusaffectedConstraints-
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| The Squid Software Foundation | The Squid Software Foundation Squid | n/a |
|
- 3.5.27
No data.
Red Hat Enterprise Linux 5
squid
Not affected
Red Hat Enterprise Linux 6
squid
Will not fix
Red Hat Enterprise Linux 6
squid34
Will not fix
Red Hat Enterprise Linux 7
squid
Fix deferred
Red Hat Enterprise Linux 8
squid
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 5 | squid | Not affected | n/a |
| Red Hat Enterprise Linux 6 | squid | Will not fix | n/a |
| Red Hat Enterprise Linux 6 | squid34 | Will not fix | n/a |
| Red Hat Enterprise Linux 7 | squid | Fix deferred | n/a |
| Red Hat Enterprise Linux 8 | squid | Not affected | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
This issue affects the versions of squid and squid34 as shipped with Red Hat Enterprise Linux 6. Red Hat Enterprise Linux 6 is now in Maintenance Support 2 Phase of the support and maintenance life cycle. This has been rated as having Low security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
Metrics
No CVSS v4.0 score for this CVE.
No CVSS v3.1 score for this CVE.
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
AV:N/AC:M/Au:N/C:N/I:N/A:P
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2021–2026- EPSS v1
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v1
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (36 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 8.31% (0.08310) | 94.77th | v5 (v2026.06.15) |
| Sep 22, 2026 | 8.31% (0.08310) | 94.68th | v5 (v2026.06.15) |
| Sep 21, 2026 | 11.00% (0.10997) | 95.76th | v5 (v2026.06.15) |
| Sep 6, 2026 | 8.61% (0.08611) | 94.73th | v5 (v2026.06.15) |
| Sep 5, 2026 | 11.00% (0.10997) | 95.67th | v5 (v2026.06.15) |
| Aug 30, 2026 | 8.61% (0.08611) | 94.70th | v5 (v2026.06.15) |
| Aug 28, 2026 | 11.00% (0.10997) | 95.64th | v5 (v2026.06.15) |
| Aug 24, 2026 | 8.61% (0.08611) | 94.67th | v5 (v2026.06.15) |
| Aug 23, 2026 | 11.00% (0.10997) | 95.63th | v5 (v2026.06.15) |
| Jun 15, 2026 | 8.94% (0.08942) | 94.56th | v5 (v2026.06.15) |
| Mar 14, 2026 | 8.73% (0.08729) | 92.37th | v4 (v2025.03.14) |
| Dec 28, 2025 | 11.21% (0.11212) | 93.27th | v4 (v2025.03.14) |
| Dec 27, 2025 | 8.01% (0.08013) | 91.83th | v4 (v2025.03.14) |
| Nov 21, 2025 | 11.21% (0.11212) | 93.21th | v4 (v2025.03.14) |
| Nov 18, 2025 | 29.57% (0.29574) | 96.34th | v4 (v2025.03.14) |
| Oct 28, 2025 | 11.21% (0.11212) | 93.17th | v4 (v2025.03.14) |
| Oct 27, 2025 | 8.01% (0.08013) | 91.72th | v4 (v2025.03.14) |
| Oct 1, 2025 | 11.21% (0.11212) | 93.27th | v4 (v2025.03.14) |
| Aug 20, 2025 | 8.01% (0.08013) | 91.72th | v4 (v2025.03.14) |
| Jul 30, 2025 | 9.09% (0.09092) | 92.31th | v4 (v2025.03.14) |
| Jun 19, 2025 | 12.65% (0.12649) | 93.62th | v4 (v2025.03.14) |
| Mar 30, 2025 | 18.68% (0.18680) | 94.77th | v4 (v2025.03.14) |
| Mar 29, 2025 | 31.87% (0.31868) | 94.99th | v4 (v2025.03.14) |
| Mar 17, 2025 | 18.68% (0.18680) | 94.78th | v4 (v2025.03.14) |
| Jul 20, 2024 | 0.73% (0.00725) | 80.88th | v3 (v2023.03.01) |
| Mar 25, 2024 | 0.73% (0.00725) | 80.25th | v3 (v2023.03.01) |
| Oct 7, 2023 | 0.67% (0.00667) | 77.35th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.95% (0.00945) | 80.74th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.05% (0.01055) | 52.13th | v2 (v2022.01.01) |
| Sep 17, 2022 | 1.05% (0.01055) | 50.47th | v2 (v2022.01.01) |
| Apr 1, 2022 | 1.05% (0.01055) | 48.43th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.05% (0.01055) | 27.52th | v2 (v2022.01.01) |
| Feb 3, 2022 | 0.78% (0.00785) | 22.12th | v1 |
| Jan 6, 2022 | 0.78% (0.00785) | 21.52th | v1 |
| Sep 1, 2021 | 0.78% (0.00785) | 52.07th | v1 |
| Apr 14, 2021 | 0.78% (0.00785) | 0.00th | v1 |
References (6)
- http://www.squid-cache.org/Advisories/SQUID-2018_3.txt x_refsource_CONFIRMVendor Advisory
- https://access.redhat.com/security/cve/CVE-2018-1172 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1569424 Issue Tracking
- https://nvd.nist.gov/vuln/detail/CVE-2018-1172
- https://www.cve.org/CVERecord?id=CVE-2018-1172
- https://zerodayinitiative.com/advisories/ZDI-18-309 x_refsource_MISCThird Party AdvisoryVDB Entry
| Link | Providers | Tags |
|---|---|---|
| http://www.squid-cache.org/Advisories/SQUID-2018_3.txt | x_refsource_CONFIRMVendor Advisory | |
| https://access.redhat.com/security/cve/CVE-2018-1172 | Vendor Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=1569424 | Issue Tracking | |
| https://nvd.nist.gov/vuln/detail/CVE-2018-1172 | ||
| https://www.cve.org/CVERecord?id=CVE-2018-1172 | ||
| https://zerodayinitiative.com/advisories/ZDI-18-309 | x_refsource_MISCThird Party AdvisoryVDB Entry |
Change history (0)
No recorded changes yet.