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Enterprise Linux DesktopOperating system · Redhat

CVE-2018-5157

HIGH · 7.5 CVSS v3.0 Published 2018-06-11
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Same-origin protections for the PDF viewer can be bypassed, allowing a malicious site to intercept messages meant for the viewer. This could allow the site to retrieve PDF files restricted to viewing by an authenticated user on a third-party website. This vulnerability affects Firefox ESR < 52.8 and Firefox < 60.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A Same-Origin Policy bypass vulnerability in Mozilla Firefox's built-in PDF viewer allows malicious websites to intercept messages intended for the PDF viewer. Attackers can exploit this to access PDF files restricted to authenticated users on third-party websites by tricking users into visiting crafted pages.

MitigationUpdate Firefox to version 60 or later (Firefox ESR to 52.8 or later) to patch the vulnerable PDF viewer component.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Enterprise Linux DesktopOperating system
Affected:= 6.0= 7.0
Enterprise Linux ServerOperating system
Affected:= 6.0= 7.0
Enterprise Linux Server AusOperating system
Affected:= 7.6
Enterprise Linux Server EusOperating system
Affected:= 7.5= 7.6
Enterprise Linux Server TusOperating system
Affected:= 7.6
Enterprise Linux WorkstationOperating system
Affected:= 6.0= 7.0
Debian LinuxOperating system
Affected:= 7.0= 8.0= 9.0
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 17.10= 18.04

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check if Firefox is installed
    Run command: rpm -qa firefox (RHEL) or dpkg -l firefox (Debian/Ubuntu) to list the Firefox package
    Affected if Firefox is not installed on the system - this CVE does not apply
  2. Determine installed Firefox version
    Run command: firefox --version or rpm -q firefox --queryformat '%{VERSION}' to get the exact Firefox version number
    Affected if The installed version falls within the vulnerable range and is older than the patched versions (Firefox versions prior to 60, Firefox ESR versions prior to 52.8)
  3. Verify PDF viewer is enabled
    In Firefox, navigate to about:config and check the value of pdfjs.disabled - if set to true, the PDF viewer is disabled
    Affected if pdfjs.disabled is false (default) - the PDF viewer is enabled and the system is potentially vulnerable when browsing untrusted websites
  4. Confirm browser usage context
    Check if Firefox is used as a primary browser or has authenticated access to PDF files on internal/intranet sites - review browser usage in enterprise workflows
    Affected if Users access authenticated PDF resources via Firefox on affected versions - the SOP bypass could allow malicious sites to intercept these requests

A user is affected if Firefox is installed with a version older than 60 (or older than ESR 52.8) and the built-in PDF viewer is enabled (pdfjs.disabled is not set to true), especially when browsing authenticated PDF resources on internal or third-party websites.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update Firefox to version 60 or later (Firefox ESR to 52.8 or later) to patch the vulnerable PDF viewer component.

Fix this in Enterprise Linux Desktop Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2018-5157 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data