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01 Record

CVE-2026-39821

Invoking failure to reject ASCII-only Punycode-encoded labels in golang.org/x/net/idna

CriticalPUBLISHEDCNA: Go
CNA base score9.6 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
View raw JSON

02 Description

Invoking failure to reject ASCII-only Punycode-encoded labels in golang.org/x/net/idna

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
1.83% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 78.7% of scored records. A rank, not a probability.
NVD base score
9.6 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
NVD analysis status
Modified. NVD last modified this record on 2026-09-17.
Red Hat severity
Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-05-22 15:01Z5 MO AGO
Last updated
2026-09-17 12:04Z1 MO AGO
Reserved
2026-04-07
Assigning CNA
Go
Record state
PUBLISHED
Severity
Critical (CVSS 9.6)
CNA CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
Weaknesses
  • CWE-1289Improper Validation of Unsafe Equivalence in InputBase
Data version
5.2
Document digest
b1bdad551703c2b2fd9b15c2e25b4688ffb490db55284c835a913073d0499cc9

05 Affected products

VendorProductVersionsPlatforms
Go standard librarynet/http0 to < 1.25.13, 1.26.0-0 to < 1.26.6, 1.27.0-0 to < 1.27.0-rc.3—
Go standard librarynet/http/internal/http20 to < 1.25.13, 1.26.0-0 to < 1.26.6, 1.27.0-0 to < 1.27.0-rc.3—
golang.org/x/netgolang.org/x/net/idna0 to < 0.55.0—

06 References

07 Fixed in

AlmaLinux 8

  • delve
    Fixed in 1.26.1-1.module_el8.10.0+4223+bd807c2e
  • git-lfs
    Fixed in 3.4.1-11.el8_10
  • go-toolset
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang-bin
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang-docs
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang-misc
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang-race
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang-src
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang-tests
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • grafana
    Fixed in 9.2.10-31.el8_10
  • grafana-pcp
    Fixed in 5.1.1-16.el8_10
  • grafana-selinux
    Fixed in 9.2.10-31.el8_10
  • osbuild-composer
    Fixed in 101.5-2.el8_10.alma.1
  • osbuild-composer-core
    Fixed in 101.5-2.el8_10.alma.1
  • osbuild-composer-worker
    Fixed in 101.5-2.el8_10.alma.1

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

AlmaLinux 9

  • git-lfs
    Fixed in 3.7.1-4.el9_8.1
  • go-toolset
    Fixed in 1.26.5-1.el9_8
  • golang
    Fixed in 1.26.5-1.el9_8
  • golang-bin
    Fixed in 1.26.5-1.el9_8
  • golang-docs
    Fixed in 1.26.5-1.el9_8
  • golang-misc
    Fixed in 1.26.5-1.el9_8
  • golang-race
    Fixed in 1.26.5-1.el9_8
  • golang-src
    Fixed in 1.26.5-1.el9_8
  • golang-tests
    Fixed in 1.26.5-1.el9_8
  • grafana
    Fixed in 10.2.6-23.el9_8
  • grafana-pcp
    Fixed in 5.1.1-17.el9_8
  • grafana-selinux
    Fixed in 10.2.6-23.el9_8
  • opentelemetry-collector
    Fixed in 0.152.1-1.el9_8
  • osbuild-composer
    Fixed in 165.1-4.el9_8.1.alma.1
  • osbuild-composer-core
    Fixed in 165.1-4.el9_8.1.alma.1
  • osbuild-composer-worker
    Fixed in 165.1-4.el9_8.1.alma.1

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

AlmaLinux 10

  • git-lfs
    Fixed in 3.7.1-5.el10_2.5
  • go-fdo-server
    Fixed in 1.0.1-2.el10_2.3
  • go-fdo-server-manufacturer
    Fixed in 1.0.1-2.el10_2.3
  • go-fdo-server-owner
    Fixed in 1.0.1-2.el10_2.3
  • go-fdo-server-rendezvous
    Fixed in 1.0.1-2.el10_2.3
  • go-toolset
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang-bin
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang-docs
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang-misc
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang-race
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang-src
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang-tests
    Fixed in 1.26.5-1.el10_2.alma.1
  • grafana
    Fixed in 10.2.6-27.el10_2
  • grafana-pcp
    Fixed in 5.3.0-7.el10_2
  • grafana-selinux
    Fixed in 10.2.6-27.el10_2
  • opentelemetry-collector
    Fixed in 0.152.1-1.el10_2
  • osbuild-composer
    Fixed in 165.1-5.el10_2.alma.1
  • osbuild-composer-core
    Fixed in 165.1-5.el10_2.alma.1
  • osbuild-composer-worker
    Fixed in 165.1-5.el10_2.alma.1
  • yggdrasil
    Fixed in 0.4.9.2-1.el10_2
  • yggdrasil-devel
    Fixed in 0.4.9.2-1.el10_2

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 8

  • delve
    Fixed in 1.26.1-1.module_el8.10.0+4223+bd807c2e
  • git-lfs
    Fixed in 3.4.1-11.el8_10
  • go-toolset
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang-bin
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang-docs
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang-misc
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang-race
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang-src
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • golang-tests
    Fixed in 1.26.5-1.module_el8.10.0+4223+bd807c2e
  • grafana
    Fixed in 9.2.10-31.el8_10
  • grafana-pcp
    Fixed in 5.1.1-16.el8_10
  • grafana-selinux
    Fixed in 9.2.10-31.el8_10
  • osbuild-composer
    Fixed in 101.5-2.el8_10.alma.1
  • osbuild-composer-core
    Fixed in 101.5-2.el8_10.alma.1
  • osbuild-composer-worker
    Fixed in 101.5-2.el8_10.alma.1

Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 9

  • git-lfs
    Fixed in 3.7.1-4.el9_8.1
  • go-toolset
    Fixed in 1.26.5-1.el9_8
  • golang
    Fixed in 1.26.5-1.el9_8
  • golang-bin
    Fixed in 1.26.5-1.el9_8
  • golang-docs
    Fixed in 1.26.5-1.el9_8
  • golang-misc
    Fixed in 1.26.5-1.el9_8
  • golang-race
    Fixed in 1.26.5-1.el9_8
  • golang-src
    Fixed in 1.26.5-1.el9_8
  • golang-tests
    Fixed in 1.26.5-1.el9_8
  • grafana
    Fixed in 10.2.6-23.el9_8
  • grafana-pcp
    Fixed in 5.1.1-17.el9_8
  • grafana-selinux
    Fixed in 10.2.6-23.el9_8
  • opentelemetry-collector
    Fixed in 0.152.1-1.el9_8
  • osbuild-composer
    Fixed in 165.1-4.el9_8.1.alma.1
  • osbuild-composer-core
    Fixed in 165.1-4.el9_8.1.alma.1
  • osbuild-composer-worker
    Fixed in 165.1-4.el9_8.1.alma.1

Derived from AlmaLinux 9. Partial coverage: only packages taken from AlmaLinux 9 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 10

  • git-lfs
    Fixed in 3.7.1-5.el10_2.5
  • go-fdo-server
    Fixed in 1.0.1-2.el10_2.3
  • go-fdo-server-manufacturer
    Fixed in 1.0.1-2.el10_2.3
  • go-fdo-server-owner
    Fixed in 1.0.1-2.el10_2.3
  • go-fdo-server-rendezvous
    Fixed in 1.0.1-2.el10_2.3
  • go-toolset
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang-bin
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang-docs
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang-misc
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang-race
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang-src
    Fixed in 1.26.5-1.el10_2.alma.1
  • golang-tests
    Fixed in 1.26.5-1.el10_2.alma.1
  • grafana
    Fixed in 10.2.6-27.el10_2
  • grafana-pcp
    Fixed in 5.3.0-7.el10_2
  • grafana-selinux
    Fixed in 10.2.6-27.el10_2
  • opentelemetry-collector
    Fixed in 0.152.1-1.el10_2
  • osbuild-composer
    Fixed in 165.1-5.el10_2.alma.1
  • osbuild-composer-core
    Fixed in 165.1-5.el10_2.alma.1
  • osbuild-composer-worker
    Fixed in 165.1-5.el10_2.alma.1
  • yggdrasil
    Fixed in 0.4.9.2-1.el10_2
  • yggdrasil-devel
    Fixed in 0.4.9.2-1.el10_2

Derived from AlmaLinux 10. Partial coverage: only packages taken from AlmaLinux 10 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

Debian 12

  • golang-golang-x-net
    No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • golang-golang-x-net
    No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • golang-golang-x-net
    Fixed in 1:0.55.0-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 14.04 LTS

  • golang-1.10
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 16.04 LTS

  • golang-1.10
    No fix yet
  • golang-1.6
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 18.04 LTS

  • golang-1.10
    No fix yet
  • golang-1.8
    No fix yet
  • golang-1.9
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 20.04 LTS

  • golang-1.13
    No fix yet
  • golang-1.14
    No fix yet
  • golang-1.18
    No fix yet
  • golang-1.20
    No fix yet
  • golang-1.21
    No fix yet
  • golang-1.22
    No fix yet
  • lxd
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 22.04 LTS

  • adsys
    No fix yet
  • containerd
    No fix yet
  • golang-1.17
    No fix yet
  • golang-1.18
    Fixed in 1.18.1-1ubuntu1.3
  • golang-1.20
    No fix yet
  • golang-1.21
    Fixed in 1.21.1-1~ubuntu22.04.4
  • golang-1.22
    No fix yet
  • golang-1.23
    Fixed in 1.23.1-1~22.04.3
  • golang-1.24
    Fixed in 1.24.13-2~22.04.2
  • golang-1.25
    No fix yet
  • golang-1.26
    No fix yet
  • golang-golang-x-net
    Fixed in 1:0.0+git20211209.491a49a+dfsg-1ubuntu0.1
  • google-guest-agent
    Fixed in 20250116.00-0ubuntu1~22.04.4
  • google-osconfig-agent
    Fixed in 20251028.00-0ubuntu2~22.04.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 24.04 LTS

  • adsys
    No fix yet
  • golang-1.21
    No fix yet
  • golang-1.22
    No fix yet
  • golang-1.23
    No fix yet
  • golang-1.24
    No fix yet
  • golang-1.25
    No fix yet
  • golang-1.26
    No fix yet
  • google-guest-agent
    No fix yet
  • google-osconfig-agent
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 26.04 LTS

  • adsys
    No fix yet
  • golang-1.23
    No fix yet
  • golang-1.24
    No fix yet
  • golang-1.25
    No fix yet
  • golang-1.26
    No fix yet
  • golang-golang-x-net
    No fix yet
  • google-guest-agent
    No fix yet
  • google-osconfig-agent
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 26.10

  • adsys
    No fix yet
  • containerd
    No fix yet
  • golang-1.26
    No fix yet
  • golang-1.27
    No fix yet
  • golang-golang-x-net
    No fix yet
  • google-guest-agent
    No fix yet
  • google-osconfig-agent
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 16.04 LTS

  • containerd
    No fix yet
  • golang-1.13
    No fix yet
  • golang-1.18
    No fix yet
  • google-guest-agent
    No fix yet
  • google-osconfig-agent
    No fix yet
  • juju-core
    No fix yet
  • lxd
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 18.04 LTS

  • containerd
    No fix yet
  • golang-1.13
    No fix yet
  • golang-1.16
    No fix yet
  • golang-1.18
    No fix yet
  • golang-golang-x-net-dev
    Fixed in 1:0.0+git20170629.c81e7f2+dfsg-2ubuntu0.1~esm3
    Available with Ubuntu Pro: https://ubuntu.com/pro
  • google-guest-agent
    No fix yet
  • google-osconfig-agent
    No fix yet
  • lxd
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 20.04 LTS

  • adsys
    No fix yet
  • containerd
    No fix yet
  • golang-1.16
    No fix yet
  • golang-golang-x-net-dev
    Fixed in 1:0.0+git20190811.74dc4d7+dfsg-1ubuntu0.1~esm3
    Available with Ubuntu Pro: https://ubuntu.com/pro
  • google-guest-agent
    No fix yet
  • google-osconfig-agent
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 22.04 LTS

  • golang-1.13
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 24.04 LTS

  • containerd
    No fix yet
  • golang-golang-x-net
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 26.04 LTS

  • containerd
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.