CVE-2026-39823: CVE-2026-27142 fixed a vulnerability in which URLs were not correctly escaped inside of a <meta> tag's <conten

Routine

MEDIUM 6.1UPGRADE

CVE-2026-39823 is a medium-severity flaw (CVSS 6.1) affecting go. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

CVE-2026-27142 fixed a vulnerability in which URLs were not correctly escaped inside of a <meta> tag's <content> attribute. If the URL content were to insert ASCII whitespaces around the '=' rune inside of the <content> attribute, the escaper would fail to similarly escape it, leading to XSS.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 76%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-05-07
Last modified	2026-10-26

Publisher (CNA): Go Project · Vendor: golang

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-07 20:16 UTCPublished CVE record published
2026-10-26 20:10 UTCUpdated Record last modified

golang go UPGRADE

Affected: < 1.25.10 · >= 1.26.0 and < 1.26.3

Fixed in: 1.25.10, 1.26.3

Safe to downgrade to: a release before 1.26.0

1. Check installed version

apt-cache policy go || rpm -q go || go --version

2. UPGRADE to 1.25.10 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade go

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade go

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.26.0 (Debian / Ubuntu)

apt-cache madison go sudo apt install go=<VERSION_BEFORE_1.26.0> sudo apt-mark hold go

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list go sudo dnf downgrade go-<VERSION_BEFORE_1.26.0> sudo dnf versionlock add go

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-39823?

go: upgrade to 1.25.10, 1.26.3. Exact commands for each OS are on this page.

Is CVE-2026-39823 being exploited?

CVE-2026-39823 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-39823 affect?

CVE-2026-39823 affects go. Severity is medium (CVSS 6.1). CVE-2026-27142 fixed a vulnerability in which URLs were not correctly escaped inside of a <meta> tag's <content> attribute. If the URL content were to insert ASCII whitespaces around the '=' rune inside of the <content> attribute, the escap

How urgent is CVE-2026-39823?

Priority 27/100. No elevated risk signals yet.

Software pages

Go (Golang) vulnerabilities

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References

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