How severe is CVE-2022-23959?

CVE-2022-23959 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2022-23959 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2022-23959?

CVE-2022-23959 primarily affects Varnish-software Varnich Cache. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2022-23959?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2022-23959 published?

CVE-2022-23959 was published on 2022-01-26 and last updated on 2026-06-17.

CVE-2022-23959

CVE-2022-23959 is a critical-severity vulnerability in Varnish-software Varnich Cache with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-444.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v2: 6.4
EPSS exploit prediction: 2% (78th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-444
Affected product: Varnish-software Varnich Cache
Published: 2022-01-26
Last modified: 2026-06-17

Description

In Varnish Cache before 6.6.2 and 7.x before 7.0.2, Varnish Cache 6.0 LTS before 6.0.10, and and Varnish Enterprise (Cache Plus) 4.1.x before 4.1.11r6 and 6.0.x before 6.0.9r4, request smuggling can occur for HTTP/1 connections.

Frequently asked questions

What is CVE-2022-23959?: In Varnish Cache before 6.6.2 and 7.x before 7.0.2, Varnish Cache 6.0 LTS before 6.0.10, and and Varnish Enterprise (Cache Plus) 4.1.x before 4.1.11r6 and 6.0.x before 6.0.9r4, request smuggling can occur for HTTP/1 connections.
How severe is CVE-2022-23959?: CVE-2022-23959 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2022-23959 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2022-23959?: CVE-2022-23959 primarily affects Varnish-software Varnich Cache. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2022-23959?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2022-23959 published?: CVE-2022-23959 was published on 2022-01-26 and last updated on 2026-06-17.

References

Affected products (10)

cpe:2.3:a:varnish-software:varnich_cache:*:*:*:*:-:*:*:*
cpe:2.3:a:varnish-software:varnich_cache:*:*:*:*:plus:*:*:*
cpe:2.3:a:varnish-software:varnich_cache:4.1:*:*:*:lts:*:*:*
cpe:2.3:a:varnish-software:varnish_cache:*:*:*:*:lts:*:*:*
cpe:2.3:a:varnish-software:varnish_cache_plus:*:*:*:*:*:*:*:*
cpe:2.3:a:varnish_cache_project:varnish_cache:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

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