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NVD / CVE Program· CNA Go

CVE-2023-39320: Arbitrary code execution via go.mod toolchain directive in cmd/go

Noroxi assessment

Priority: Plan (action score 40/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.7% (FIRST EPSS); higher than 77.8% 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: Go toolchain cmd/go 1.21.1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Add it to your regular patch cycle. Upgrade to Go toolchain cmd/go 1.21.1 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 go.mod toolchain directive, introduced in Go 1.21, can be leveraged to execute scripts and binaries relative to the root of the module when the "go" command was executed within the module. This applies to modules downloaded using the "go" command from the module proxy, as well as modules downloaded directly using VCS software.

CriticalCVSS 9.8 · v3.1—Proof of concept Fix available
Published
Sep 8, 2023
Updated
Jun 17, 2026
EPSS
1.7% · 77th percentile

Report tools

JSON

Action score

40

Plan

Add it to your regular patch cycle.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 1.7%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

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

Follow CVE-2023-39320

When you'll hear from us

  • when it enters CISA KEV
  • 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
golanggo

Affected versions

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

  • golang go1.21.0 and later · before 1.21.1

Versions reported by the vendor

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

  • Go toolchain cmd/go

    • 1.21.0-0 and later · before 1.21.1affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Gotoolchainfrom 1.21.0-0 · before 1.21.11.21.1
openSUSE:Leap 15.4go1.21before 1.21.1-150000.1.6.11.21.1-150000.1.6.1
openSUSE:Leap 15.4go1.21-opensslbefore 1.21.4.1-150000.1.5.11.21.4.1-150000.1.5.1
openSUSE:Tumbleweedgo1.21before 1.21.1-1.11.21.1-1.1
SUSE:Linux Enterprise Module for Development Tools 15 SP4go1.21before 1.21.1-150000.1.6.11.21.1-150000.1.6.1
SUSE:Linux Enterprise Module for Development Tools 15 SP4go1.21-opensslbefore 1.21.4.1-150000.1.5.11.21.4.1-150000.1.5.1
SUSE:Package Hub 12gobefore 1.21-41.11.21-41.1
SUSE:Package Hub 12go1.21before 1.21.3-2.11.21.3-2.1

Same product

golang: all records

Other highest-scoring records for the same primary product.

  • CVE-2018-7187The "go get" implementation in Go 1.9.4, when the -insecure command-line option is used, does not validate the import path (get/vcs.go only
    54Plan
  • CVE-2018-16873In Go before 1.10.6 and 1.11.x before 1.11.3, the "go get" command is vulnerable to remote code execution when executed with the -u flag and
    52Plan
  • CVE-2021-38297Go before 1.16.9 and 1.17.x before 1.17.2 has a Buffer Overflow via large arguments in a function invocation from a WASM module, when GOARCH
    42Plan

Published before and after this one in the same product

  • ← EarlierCVE-2023-39318Sep 8, 2023 · Improper handling of HTML-like comments in script contexts in html/template
    24Monitor
  • ← EarlierCVE-2023-39319Sep 8, 2023 · Improper handling of special tags within script contexts in html/template
    24Monitor
  • Later →CVE-2023-39321Sep 8, 2023 · Panic when processing post-handshake message on QUIC connections in crypto/tls
    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
Go toolchain cmd/go1.21.1Vendor (CNA)
Go:toolchain1.21.1Package registry (OSV)
opensuse:go1.211.21.1-150000.1.6.1 · openSUSE:Leap 15.4Package registry (OSV)
opensuse:go1.21-openssl1.21.4.1-150000.1.5.1 · openSUSE:Leap 15.4Package registry (OSV)
suse:go1.21-41.1 · SUSE:Package Hub 12Package registry (OSV)
suse:go1.211.21.1-150000.1.6.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP4Package registry (OSV)
suse:go1.21-openssl1.21.4.1-150000.1.5.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP4Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:12024-02-24

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.

  1. Published
  2. First PoC+168 d
  3. TodayOct 29, 2026+1146 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

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

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

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-94 · Improper Control of Generation of Code ('Code Injection')

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.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

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

All records