Vulnerability-Lookup

ALSA-2026:22112

Vulnerability from osv_almalinux – Published: 2026-06-01 00:00 – Updated: 2026-09-29 13:08 – Source website

Summary

Important: go-toolset:rhel8 security update

Details

Go Toolset provides the Go programming language tools and libraries. Go is alternatively known as golang.

Security Fix(es):

net/mail: golang: net/mail: Denial of Service via pathological email address parsing (CVE-2026-42499)
cmd/go: golang: Go command (cmd/go): Integrity bypass due to checksum validation flaw via malicious module proxy (CVE-2026-42501)
html/template: golang: Go html/template: Cross-Site Scripting via improper URL escaping in meta tag content (CVE-2026-39823)
cmd/go: golang: Go 'go bug' command: Arbitrary file overwrite via symlink attack (CVE-2026-39819)
net/http/internal/http2: golang: golang.org/x/net: Go HTTP/2: Denial of Service via malformed SETTINGS_MAX_FRAME_SIZE frame (CVE-2026-33814)
net/mail: golang: Go net/mail: Denial of Service via crafted email inputs (CVE-2026-39820)
net: golang: Go net package: Denial of Service via long CNAME response in LookupCNAME (CVE-2026-33811)
net/http/httputil: golang: net/http/httputil: ReverseProxy forwards hidden query parameters, potentially bypassing security controls (CVE-2026-39825)
cmd/go: golang: Go tool pack: Arbitrary file write via malicious archive extraction (CVE-2026-39817)
html/template: golang: html/template: Cross-site scripting due to incorrect script tag escaping (CVE-2026-39826)
net: golang: Go net package: Denial of Service via NUL byte in Dial and LookupPort on Windows (CVE-2026-39836)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

References

URL

Type

	https://access.redhat.com/errata/RHSA-2026:22112	ADVISORY
	https://access.redhat.com/security/cve/CVE-2026-33811	REPORT
	https://access.redhat.com/security/cve/CVE-2026-33814	REPORT
	https://access.redhat.com/security/cve/CVE-2026-39817	REPORT
	https://access.redhat.com/security/cve/CVE-2026-39819	REPORT
	https://access.redhat.com/security/cve/CVE-2026-39820	REPORT
	https://access.redhat.com/security/cve/CVE-2026-39823	REPORT
	https://access.redhat.com/security/cve/CVE-2026-39825	REPORT
	https://access.redhat.com/security/cve/CVE-2026-39826	REPORT
	https://access.redhat.com/security/cve/CVE-2026-39836	REPORT
	https://access.redhat.com/security/cve/CVE-2026-42499	REPORT
	https://access.redhat.com/security/cve/CVE-2026-42501	REPORT
	https://bugzilla.redhat.com/2467822	REPORT
	https://errata.almalinux.org/8/ALSA-2026-22112.html	ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "AlmaLinux:8",
        "name": "delve"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.25.2-1.module_el8.10.0+4074+24330916"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "AlmaLinux:8",
        "name": "go-toolset"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.25.10-1.module_el8.10.0+4187+c45165c4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "AlmaLinux:8",
        "name": "golang"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.25.10-1.module_el8.10.0+4187+c45165c4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "AlmaLinux:8",
        "name": "golang-bin"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.25.10-1.module_el8.10.0+4187+c45165c4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "AlmaLinux:8",
        "name": "golang-docs"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.25.10-1.module_el8.10.0+4187+c45165c4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "AlmaLinux:8",
        "name": "golang-misc"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.25.10-1.module_el8.10.0+4187+c45165c4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "AlmaLinux:8",
        "name": "golang-race"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.25.10-1.module_el8.10.0+4187+c45165c4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "AlmaLinux:8",
        "name": "golang-src"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.25.10-1.module_el8.10.0+4187+c45165c4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "AlmaLinux:8",
        "name": "golang-tests"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.25.10-1.module_el8.10.0+4187+c45165c4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "Go Toolset provides the Go programming language tools and libraries. Go is alternatively known as golang.   \n\nSecurity Fix(es):  \n\n  * net/mail: golang: net/mail: Denial of Service via pathological email address parsing (CVE-2026-42499)\n  * cmd/go: golang: Go command (cmd/go): Integrity bypass due to checksum validation flaw via malicious module proxy (CVE-2026-42501)\n  * html/template: golang: Go html/template: Cross-Site Scripting via improper URL escaping in meta tag content (CVE-2026-39823)\n  * cmd/go: golang: Go \u0027go bug\u0027 command: Arbitrary file overwrite via symlink attack (CVE-2026-39819)\n  * net/http/internal/http2: golang: golang.org/x/net: Go HTTP/2: Denial of Service via malformed SETTINGS_MAX_FRAME_SIZE frame (CVE-2026-33814)\n  * net/mail: golang: Go net/mail: Denial of Service via crafted email inputs (CVE-2026-39820)\n  * net: golang: Go net package: Denial of Service via long CNAME response in LookupCNAME (CVE-2026-33811)\n  * net/http/httputil: golang: net/http/httputil: ReverseProxy forwards hidden query parameters, potentially bypassing security controls (CVE-2026-39825)\n  * cmd/go: golang: Go tool pack: Arbitrary file write via malicious archive extraction (CVE-2026-39817)\n  * html/template: golang: html/template: Cross-site scripting due to incorrect script tag escaping (CVE-2026-39826)\n  * net: golang: Go net package: Denial of Service via NUL byte in Dial and LookupPort on Windows (CVE-2026-39836)\n\n\nFor more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.\n",
  "id": "ALSA-2026:22112",
  "modified": "2026-09-29T13:08:10Z",
  "published": "2026-06-01T00:00:00Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://access.redhat.com/errata/RHSA-2026:22112"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-33811"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-33814"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-39817"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-39819"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-39820"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-39823"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-39825"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-39826"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-39836"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-42499"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2026-42501"
    },
    {
      "type": "REPORT",
      "url": "https://bugzilla.redhat.com/2467822"
    },
    {
      "type": "ADVISORY",
      "url": "https://errata.almalinux.org/8/ALSA-2026-22112.html"
    }
  ],
  "related": [
    "CVE-2026-42499",
    "CVE-2026-42501",
    "CVE-2026-39823",
    "CVE-2026-39819",
    "CVE-2026-33814",
    "CVE-2026-39820",
    "CVE-2026-33811",
    "CVE-2026-39825",
    "CVE-2026-39817",
    "CVE-2026-39826",
    "CVE-2026-39836"
  ],
  "summary": "Important: go-toolset:rhel8 security update"
}

CVE-2026-42501 (GCVE-0-2026-42501)

Vulnerability from cvelistv5 – Published: 2026-05-07 19:41 – Updated: 2026-05-08 15:48

Title

Malicious module proxy can bypass checksum database in cmd/go

Summary

A malicious module proxy can exploit a flaw in the go command's validation of module checksums to bypass checksum database validation. This vulnerability affects any user using an untrusted module proxy (GOMODPROXY) or checksum database (GOSUMDB). A malicious module proxy can serve altered versions of the Go toolchain. When selecting a different version of the Go toolchain than the currently installed toolchain (due to the GOTOOLCHAIN environment variable, or a go.work or go.mod with a toolchain line), the go command will download and execute a toolchain provided by the module proxy. A malicious module proxy can bypass checksum database validation for this downloaded toolchain. Since this vulnerability affects the security of toolchain downloads, setting GOTOOLCHAIN to a fixed version is not sufficient. You must upgrade your base Go toolchain. The go tool always validates the hash of a toolchain before executing it, so fixed versions will refuse to execute any cached, altered versions of the toolchain. The go tool trusts go.sum files to contain accurate hashes of the current module's dependencies. A malicious proxy exploiting this vulnerability to serve an altered module will have caused an incorrect hash to be recorded in the go.sum. Users who have configured a non-trusted GOPROXY can determine if they have been affected by running "rm go.sum ; go mod tidy ; go mod verify", which will revalidate all dependencies of the current module. The specific flaw in more detail: The go command consults the checksum database to validate downloaded modules, when a module is not listed in the go.sum file. It verifies that the module hash reported by the checksum database matches the hash of the downloaded module. If, however, the checksum database returns a successful response that contains no entry for the module, the go command incorrectly permitted validation to succeed. A module proxy may mirror or proxy the checksum database, in which case the go command will not connect to the checksum database directly. Checksums reported by the checksum database are cryptographically signed, so a malicious proxy cannot alter the reported checksum for a module. However, a proxy which returns an empty checksum response, or a checksum response for an unrelated module, could cause the go command to proceed as if a downloaded module has been validated.

Severity

7.5 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-05-08 15:48 UTC

CWE

CWE-347 - Improper Verification of Cryptographic Signature

Assigner

Go Google root Scorecard

References

4 references

URL	Tags
https://go.dev/cl/775321
https://go.dev/issue/79070
https://groups.google.com/g/golang-announce/c/qcC…
https://pkg.go.dev/vuln/GO-2026-4984

Impacted products

1 product

Vendor	Product	Version
Go toolchain	cmd/go	Affected: 0 , < 1.25.10 (semver) Affected: 1.26.0-0 , < 1.26.3 (semver)

Credits

Mundur (https://github.com/M0nd0R)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "HIGH",
              "attackVector": "NETWORK",
              "availabilityImpact": "HIGH",
              "baseScore": 7.5,
              "baseSeverity": "HIGH",
              "confidentialityImpact": "HIGH",
              "integrityImpact": "HIGH",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "REQUIRED",
              "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-42501",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-08T15:48:05.053316Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-347",
                "description": "CWE-347 Improper Verification of Cryptographic Signature",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-08T15:48:47.404Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://pkg.go.dev",
          "defaultStatus": "unaffected",
          "packageName": "cmd/go",
          "product": "cmd/go",
          "vendor": "Go toolchain",
          "versions": [
            {
              "lessThan": "1.25.10",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThan": "1.26.3",
              "status": "affected",
              "version": "1.26.0-0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "Mundur (https://github.com/M0nd0R)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "A malicious module proxy can exploit a flaw in the go command\u0027s validation of module checksums to bypass checksum database validation. This vulnerability affects any user using an untrusted module proxy (GOMODPROXY) or checksum database (GOSUMDB). A malicious module proxy can serve altered versions of the Go toolchain. When selecting a different version of the Go toolchain than the currently installed toolchain (due to the GOTOOLCHAIN environment variable, or a go.work or go.mod with a toolchain line), the go command will download and execute a toolchain provided by the module proxy. A malicious module proxy can bypass checksum database validation for this downloaded toolchain. Since this vulnerability affects the security of toolchain downloads, setting GOTOOLCHAIN to a fixed version is not sufficient. You must upgrade your base Go toolchain. The go tool always validates the hash of a toolchain before executing it, so fixed versions will refuse to execute any cached, altered versions of the toolchain. The go tool trusts go.sum files to contain accurate hashes of the current module\u0027s dependencies. A malicious proxy exploiting this vulnerability to serve an altered module will have caused an incorrect hash to be recorded in the go.sum. Users who have configured a non-trusted GOPROXY can determine if they have been affected by running \"rm go.sum ; go mod tidy ; go mod verify\", which will revalidate all dependencies of the current module. The specific flaw in more detail: The go command consults the checksum database to validate downloaded modules, when a module is not listed in the go.sum file. It verifies that the module hash reported by the checksum database matches the hash of the downloaded module. If, however, the checksum database returns a successful response that contains no entry for the module, the go command incorrectly permitted validation to succeed. A module proxy may mirror or proxy the checksum database, in which case the go command will not connect to the checksum database directly. Checksums reported by the checksum database are cryptographically signed, so a malicious proxy cannot alter the reported checksum for a module. However, a proxy which returns an empty checksum response, or a checksum response for an unrelated module, could cause the go command to proceed as if a downloaded module has been validated."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-347: Improper Verification of Cryptographic Signature",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-07T19:41:19.691Z",
        "orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
        "shortName": "Go"
      },
      "references": [
        {
          "url": "https://go.dev/cl/775321"
        },
        {
          "url": "https://go.dev/issue/79070"
        },
        {
          "url": "https://groups.google.com/g/golang-announce/c/qcCIEXso47M"
        },
        {
          "url": "https://pkg.go.dev/vuln/GO-2026-4984"
        }
      ],
      "title": "Malicious module proxy can bypass checksum database in cmd/go"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
    "assignerShortName": "Go",
    "cveId": "CVE-2026-42501",
    "datePublished": "2026-05-07T19:41:19.691Z",
    "dateReserved": "2026-04-28T00:21:12.791Z",
    "dateUpdated": "2026-05-08T15:48:47.404Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

ALSA-2026:22112

CVE-2026-42501 (GCVE-0-2026-42501)

Tags

Sightings

Nomenclature

Related by attack behaviour