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NVD / CVE Program· CNA NCSC.ch

CVE-2022-39956: Partial rule set bypass in OWASP ModSecurity Core Rule Set for HTTP multipart requests using character encoding in the Content-Type or…

CriticalCVSS 9.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 39/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.2% (FIRST EPSS); higher than 68.8% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: modsecurity-crs (Debian:10) 3.2.3-0+deb10u3; modsecurity-crs (Debian:11) 3.3.4-1~deb11u1; modsecurity-crs (Debian:12) 3.3.4-1.
  • Severity is disputed: the assigning authority (CNA) scores it 7.3, NVD 9.8.

Low priority for now. Upgrade to modsecurity-crs (Debian:10) 3.2.3-0+deb10u3; modsecurity-crs (Debian:11) 3.3.4-1~deb11u1; modsecurity-crs (Debian:12) 3.3.4-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

The OWASP ModSecurity Core Rule Set (CRS) is affected by a partial rule set bypass for HTTP multipart requests by submitting a payload that uses a character encoding scheme via the Content-Type or the deprecated Content-Transfer-Encoding multipart MIME header fields that will not be decoded and inspected by the web application firewall engine and the rule set. The multipart payload will therefore bypass detection. A vulnerable backend that supports these encoding schemes can potentially be exploited. The legacy CRS versions 3.0.x and 3.1.x are affected, as well as the currently supported versions 3.2.1 and 3.3.2. Integrators and users are advised upgrade to 3.2.2 and 3.3.3 respectively. The mitigation against these vulnerabilities depends on the installation of the latest ModSecurity version (v2.9.6 / v3.0.8).

Published
Sep 20, 2022
Updated
Jun 17, 2026
EPSS
1.2% · 68th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.2%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
9.8
CNA · NCSC.ch
7.3
2.5 point gap

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2022-39956

When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
owaspowasp modsecurity core rule set
fedoraprojectfedora
debiandebian linux

Versions reported by the vendor

Affected version ranges reported by the assigning authority (NCSC.ch). Independent of NVD's CPE analysis and usually ahead of it.

  • OWASP ModSecurity Core Rule Set

    • 3.0.x, 3.1.xaffected
    • unspecified and later · up to and including 3.2.1affected
    • unspecified and later · up to and including 3.3.2affected
Affected versions · NVD (6)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux10.0
  • fedoraproject fedora35
  • fedoraproject fedora36
  • fedoraproject fedora37
  • owasp owasp modsecurity core rule set3.0.0 and later · before 3.2.2
  • owasp owasp modsecurity core rule set3.3.0 and later · before 3.3.3

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:10modsecurity-crsbefore 3.2.3-0+deb10u33.2.3-0+deb10u3
Debian:11modsecurity-crsbefore 3.3.4-1~deb11u13.3.4-1~deb11u1
Debian:12modsecurity-crsbefore 3.3.4-13.3.4-1

Same product

owasp: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-35368OWASP ModSecurity Core Rule Set 3.1.x before 3.1.2, 3.2.x before 3.2.1, and 3.3.x before 3.3.2 is affected by a Request Body Bypass via a…
    40Plan
  • CVE-2022-39955Partial rule set bypass in OWASP ModSecurity Core Rule Set by submitting a specially crafted HTTP Content-Type header
    39Monitor
  • CVE-2020-22669Modsecurity owasp-modsecurity-crs 3.2.0 (Paranoia level at PL1) has a SQL injection bypass vulnerability.
    39Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2018-16384Sep 2, 2018 · A SQL injection bypass (aka PL1 bypass) exists in OWASP ModSecurity Core Rule Set (owasp-modsecurity-crs) through v3.1.0-rc3 via {`a`b}…
    31Monitor
  • Later →CVE-2022-39957Sep 20, 2022 · Response body bypass in OWASP ModSecurity Core Rule Set via a specialy crafted charset in the HTTP Accept header
    30Monitor
  • Later →CVE-2022-39958Sep 20, 2022 · Response body bypass in OWASP ModSecurity Core Rule Set via repeated HTTP Range header submission with a small byte range
    30Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:modsecurity-crs3.3.4-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Not on record for this CVE: EPSS history · patch commit or PR link · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-863 · Incorrect Authorization

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records