CVE-2012-5851: html/parser/XSSAuditor.cpp in WebCore in WebKit, as used in Google Chrome through 22 and Safari 5.1.7, does no

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MEDIUM 4.3MITIGATEUPGRADEDOWNGRADE

CVE-2012-5851 is a medium-severity flaw (CVSS 4.3) affecting webkit, chrome, safari. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

html/parser/XSSAuditor.cpp in WebCore in WebKit, as used in Google Chrome through 22 and Safari 5.1.7, does not consider all possible output contexts of reflected data, which makes it easier for remote attackers to bypass a cross-site scripting (XSS) protection mechanism via a crafted string, aka rdar problem 12019108.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	4.3 (Medium)
EPSS exploit chance	2.3% (top 17%)
CISA exploited list	No
Weakness	CWE-79
Published	2012-11-15
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: apple · google

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2012-11-15 11:58 UTCPublished CVE record published
2026-06-16 23:47 UTCUpdated Record last modified

apple webkit MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

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

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

google chrome UPGRADE

Affected: <= 22.0.1229.96 · 22.0.1229.0 · 22.0.1229.1 · 22.0.1229.2 · 22.0.1229.3 · 22.0.1229.4 · 22.0.1229.6 · 22.0.1229.7

Fixed in: newer than 22.0.1229.96

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 22.0.1229.96 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade chrome

Note

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

apple safari DOWNGRADE

Affected: 5.1.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.1.7

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 5.1.7 (Debian / Ubuntu)

apt-cache madison safari sudo apt install safari=<VERSION_BEFORE_5.1.7> sudo apt-mark hold safari

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list safari sudo dnf downgrade safari-<VERSION_BEFORE_5.1.7> sudo dnf versionlock add safari

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.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: WebKit Cross-Site Scripting Filter - 'Cross-Site ScriptingAuditor.cpp' Security Bypass

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-2012-5851?

webkit: mitigate or apply the listed mitigation; chrome: upgrade to newer than 22.0.1229.96; safari: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2012-5851 being exploited?

CVE-2012-5851 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-2012-5851 affect?

CVE-2012-5851 affects webkit, chrome, safari. Severity is medium (CVSS 4.3). html/parser/XSSAuditor.cpp in WebCore in WebKit, as used in Google Chrome through 22 and Safari 5.1.7, does not consider all possible output contexts of reflected data, which makes it easier for remote attackers to bypass a cross-site scrip

How urgent is CVE-2012-5851?

Priority 41/100. Public exploit reference

Software pages

Safari vulnerabilities · Google Chrome vulnerabilities · WebKit vulnerabilities · Apple Safari and WebKit vulnerabilities

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References

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