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Ubuntu LinuxOperating system · Canonical

CVE-2015-1803

HIGH · 8.5 CVSS v2.0 Published 2015-03-20
Fix available
A fix is available. Upgrade to after 1.4.8 or later.
See remediation →
91/100
Remediation priority · Urgent
Remotely reachable 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
The bdfReadCharacters function in bitmap/bdfread.c in X.Org libXfont before 1.4.9 and 1.5.x before 1.5.1 does not properly handle character bitmaps it cannot read, which allows remote authenticated users to cause a denial of service (NULL pointer dereference and crash) and possibly execute arbitrary code via a crafted BDF font file.

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

The vulnerability exists in libXfont's BDF font file parser (bdfReadCharacters function in bitmap/bdfread.c). When processing BDF font files containing character bitmaps the parser cannot properly read, the function fails to handle the error condition correctly, leading to a NULL pointer dereference. This can cause a denial of service (crash) and potentially allow arbitrary code execution via crafted malicious BDF font files.

MitigationUpdate libXfont to version 1.4.9 or later (for 1.4.x) or 1.5.1 or later (for 1.5.x). Additionally, restrict or validate BDF font files from untrusted sources before processing.

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
Ubuntu LinuxOperating system
Affected:= 10.04= 12.04= 14.04= 14.10
Debian LinuxOperating system
Affected:= 7.0
LibxfontApplication
Affected:<= 1.4.8= 1.5.0

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
M
Authentication
Single
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:M/Au:S/C:C/I:C/A:C

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. Verify libXfont is installed
    Run `dpkg -l libxfont1` on Debian/Ubuntu, or `rpm -q libXfont` on RHEL-based systems, or check for the library file in `/usr/lib/` or `/usr/lib64/`
    Affected if libXfont is not installed or the package is missing
  2. Check installed libXfont version
    Run `dpkg -s libxfont1` (Debian/Ubuntu) or `rpm -qi libXfont` (RHEL) and note the Version field; alternatively, use `strings /usr/lib/libXfont.so.6 | grep -i "libXfont"` to find version strings in the shared library
    Affected if Version is 1.4.8 or earlier, or exactly 1.5.0
  3. Identify processes or services that parse BDF fonts
    Check for X Font Server (xfs), X11 applications loading fonts from untrusted sources, or font rendering tools like `xfd -fn <bdf-font>`; review running processes with `ps aux | grep -E 'xfs|xfd|X'
    Affected if BDF font files from untrusted or external sources are being processed by libXfont
  4. Audit BDF font files on the system
    Search for .bdf font files using `find / -name "*.bdf" 2>/dev/null` and review which applications or services load these fonts
    Affected if System has BDF font files that could be parsed by the vulnerable libXfont library

A system is affected if libXfont version is <= 1.4.8 or exactly 1.5.0 AND the library is actively used to parse BDF font files, particularly from untrusted or external sources.

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
Upgrade available Upgrade to a release after 1.4.8
Interim mitigation

Update libXfont to version 1.4.9 or later (for 1.4.x) or 1.5.1 or later (for 1.5.x). Additionally, restrict or validate BDF font files from untrusted sources before processing.

Fix this in Ubuntu Linux Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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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-2015-1803 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