varnish: denial of service via colon-starting reason phrase
Published Aug 11, 2022
7.5
HIGHCVSS 3.1
EPSS 1.39%
Description
In Varnish Cache 7.0.0, 7.0.1, 7.0.2, and 7.1.0, it is possible to cause the Varnish Server to assert and automatically restart through forged HTTP/1 backend responses. An attack uses a crafted reason phrase of the backend response status line. This is fixed in 7.0.3 and 7.1.1.
Affected products
No data.
Configuration 1
- 7.0.0
- 7.0.1
- 7.0.2
- 7.1.0
Configuration 2
- 35
- 36
No data.
Red Hat Enterprise Linux 8
varnish-modules
Not affected
Red Hat Enterprise Linux 8
varnish:6/varnish
Not affected
Red Hat Enterprise Linux 8
varnish:6/varnish-modules
Not affected
Red Hat Enterprise Linux 9
varnish
Not affected
Red Hat Enterprise Linux 9
varnish-modules
Not affected
Red Hat Software Collections
rh-varnish6-jemalloc
Not affected
Red Hat Software Collections
rh-varnish6-varnish
Not affected
Red Hat Software Collections
rh-varnish6-varnish-modules
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 8 | varnish-modules | Not affected | n/a |
| Red Hat Enterprise Linux 8 | varnish:6/varnish | Not affected | n/a |
| Red Hat Enterprise Linux 8 | varnish:6/varnish-modules | Not affected | n/a |
| Red Hat Enterprise Linux 9 | varnish | Not affected | n/a |
| Red Hat Enterprise Linux 9 | varnish-modules | Not affected | n/a |
| Red Hat Software Collections | rh-varnish6-jemalloc | Not affected | n/a |
| Red Hat Software Collections | rh-varnish6-varnish | Not affected | n/a |
| Red Hat Software Collections | rh-varnish6-varnish-modules | Not affected | n/a |
No package ranges for this CVE.
Remediation
Red Hat mitigation
As mentioned in the upstream security advisory, If upgrading Varnish is not possible, it is possible to mitigate the problem by adding the following snippet at the beginning of the vcl_backend_response VCL function: ``` sub vcl_backend_response { set beresp.status = beresp.status; } ``` By setting the status code to itself as described above, the reason field will automatically be reset to the standard value for the given status code, or “Unknown HTTP Status” if no standard value exists for that code. This would overwrite any existing attack content in the reason field.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
1 other source (CISA ADP) ▾
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
NoTechnical Impact
PartialDecision
n/aAssessed Oct 20, 2025 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (15 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 1.39% (0.01386) | 71.23th | v5 (v2026.06.15) |
| Jun 15, 2026 | 1.14% (0.01138) | 62.28th | v5 (v2026.06.15) |
| Mar 17, 2025 | 0.26% (0.00258) | 47.23th | v4 (v2025.03.14) |
| Dec 12, 2024 | 0.15% (0.00153) | 52.91th | v3 (v2023.03.01) |
| Apr 1, 2024 | 0.15% (0.00153) | 50.70th | v3 (v2023.03.01) |
| Jan 21, 2024 | 0.13% (0.00128) | 47.41th | v3 (v2023.03.01) |
| Nov 8, 2023 | 0.12% (0.00116) | 45.21th | v3 (v2023.03.01) |
| Sep 12, 2023 | 0.11% (0.00108) | 43.00th | v3 (v2023.03.01) |
| Aug 17, 2023 | 0.09% (0.00091) | 38.14th | v3 (v2023.03.01) |
| Jul 11, 2023 | 0.07% (0.00066) | 27.37th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.06% (0.00056) | 21.13th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.02% (0.01018) | 40.69th | v2 (v2022.01.01) |
| Nov 26, 2022 | 1.02% (0.01018) | 39.51th | v2 (v2022.01.01) |
| Aug 31, 2022 | 0.95% (0.00954) | 34.46th | v2 (v2022.01.01) |
| Aug 11, 2022 | 0.89% (0.00885) | 25.96th | v2 (v2022.01.01) |
References (8)
- https://access.redhat.com/security/cve/CVE-2022-38150 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2117692 Issue Tracking
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M4KVVCIQVINQQ2D7ORNARSYALMJUMP3I/ vendor-advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TW3X4PEKC5C736SCKE2UG3Y7JWKMD2K6/ vendor-advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/V2BUKFICLZBXESLQ3MXMIG3G52RZURFK/ vendor-advisory
- https://nvd.nist.gov/vuln/detail/CVE-2022-38150
- https://varnish-cache.org/security/VSV00009.html MitigationVendor Advisory
- https://www.cve.org/CVERecord?id=CVE-2022-38150
Change history (0)
No recorded changes yet.