CVE-2021-45087: XSS can occur in GNOME Web (aka Epiphany) before 40.4 and 41.x before 41.1 when View Source mode or Reader mod

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MEDIUM 6.1WATCHLISTUPGRADEMITIGATE

CVE-2021-45087 is a medium-severity flaw (CVSS 6.1) affecting epiphany, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

XSS can occur in GNOME Web (aka Epiphany) before 40.4 and 41.x before 41.1 when View Source mode or Reader mode is used, as demonstrated by a a page title.

Why this priority

Public exploit reference
On your watchlist

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	1.6% (top 24%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-12-16
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · gnome

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-12-16 03:15 UTCPublished CVE record published
2026-06-17 04:13 UTCUpdated Record last modified

gnome epiphany UPGRADE

Affected: < 40.4 · >= 41.0 and < 41.1

Fixed in: 40.4, 41.1

Safe to downgrade to: a release before 41.0

1. Check installed version

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

2. UPGRADE to 40.4 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade epiphany

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 41.0 (Debian / Ubuntu)

apt-cache madison epiphany sudo apt install epiphany=<VERSION_BEFORE_41.0> sudo apt-mark hold epiphany

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

dnf --showduplicates list epiphany sudo dnf downgrade epiphany-<VERSION_BEFORE_41.0> sudo dnf versionlock add epiphany

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.

debian debian linux MITIGATE

Affected: 10.0 · 11.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2021-45087?

epiphany: upgrade to 40.4, 41.1; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-45087 being exploited?

CVE-2021-45087 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-2021-45087 affect?

CVE-2021-45087 affects epiphany, debian linux. Severity is medium (CVSS 6.1). XSS can occur in GNOME Web (aka Epiphany) before 40.4 and 41.x before 41.1 when View Source mode or Reader mode is used, as demonstrated by a a page title.

How urgent is CVE-2021-45087?

Priority 50/100. Public exploit reference; On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

CVE-2023-26081 HIGH 7.5 UPGRADE MITIGATE In Epiphany (aka GNOME Web) through 43.0, untrusted web content can trick users into exfiltrating passwords, b
CVE-2022-29536 HIGH 7.5 UPGRADE MITIGATE In GNOME Epiphany before 41.4 and 42.x before 42.2, an HTML document can trigger a client buffer overflow (in
CVE-2021-45088 MEDIUM 6.1 UPGRADE MITIGATE XSS can occur in GNOME Web (aka Epiphany) before 40.4 and 41.x before 41.1 via an error page.
CVE-2021-45086 MEDIUM 6.1 UPGRADE MITIGATE XSS can occur in GNOME Web (aka Epiphany) before 40.4 and 41.x before 41.1 because a server's suggested_filena
CVE-2021-45085 MEDIUM 6.1 UPGRADE MITIGATE XSS can occur in GNOME Web (aka Epiphany) before 40.4 and 41.x before 41.1 via an about: page, as demonstrated

References

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