PatchTheCVECVE-2015-8668: Heap-based buffer overflow in the PackBitsPreEncode function in tif_packbits.c in bmp2tiff in libtiff 4.0.6 an
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This week
CRITICAL 9.8REMOTEWATCHLISTUPGRADEDOWNGRADEMITIGATE
CVE-2015-8668 is a critical-severity flaw (CVSS 9.8) affecting libtiff, vm server, linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Heap-based buffer overflow in the PackBitsPreEncode function in tif_packbits.c in bmp2tiff in libtiff 4.0.6 and earlier allows remote attackers to execute arbitrary code or cause a denial of service via a large width field in a BMP image.
Why this priority
- Critical severity
- EPSS top 3%: very likely to be exploited
- Public exploit reference
- Remotely exploitable, no login, no user action
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 9.8 (Critical) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 13.7% (top 3%) |
| CISA exploited list | No |
| Weakness | CWE-787 |
| Published | 2016-01-08 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
libtiff libtiff UPGRADE
Affected: <= 4.0.6
Fixed in: newer than 4.0.6
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy libtiff || rpm -q libtiff || libtiff --version
2. UPGRADE to newer than 4.0.6 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade libtiff
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade libtiff
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
oracle vm server DOWNGRADE
Affected: 3.3 · 3.4
Fixed in: no fixed release known
Safe to downgrade to: a release before 3.3
1. Check installed version
apt-cache policy vm-server || rpm -q vm-server || vm-server --version
2. No fixed release: DOWNGRADE to a release before 3.3 (Debian / Ubuntu)
apt-cache madison vm-server
sudo apt install vm-server=<VERSION_BEFORE_3.3>
sudo apt-mark hold vm-server
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list vm-server
sudo dnf downgrade vm-server-<VERSION_BEFORE_3.3>
sudo dnf versionlock add vm-server
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.
oracle linux MITIGATE
Affected: 6 · 7
Fixed in: no fixed release known
Safe to downgrade to: a release before 6
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.
redhat enterprise linux MITIGATE
Affected: 6.0 · 7.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 6.0
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.
redhat enterprise linux desktop MITIGATE
Affected: 6.0 · 7.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 6.0
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.
redhat enterprise linux workstation MITIGATE
Affected: 6.0 · 7.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 6.0
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.
Exact fixes by distribution
A distro patch exists: prefer upgrading over downgrading.
Fedora 46 · rust-ingredients · FIXED · 0.3.3-2.fc46 · FEDORA-2026-0b3d9feffd · source
sudo dnf upgrade --advisory=FEDORA-2026-0b3d9feffd
Fedora ELN · dpkg · FIXED · 1.23.11-2.eln159 · FEDORA-2026-732e4ac21b · source
sudo dnf upgrade --advisory=FEDORA-2026-732e4ac21b
Debian 12 · tiff · FIXED · 4.0.6-3
sudo apt update && sudo apt install --only-upgrade tiff
dpkg --compare-versions "$(dpkg-query -W -f='${Version}' tiff)" ge "4.0.6-3" && echo PATCHED || echo STILL-VULNERABLE
Debian 13 · tiff · FIXED · 4.0.6-3
sudo apt update && sudo apt install --only-upgrade tiff
dpkg --compare-versions "$(dpkg-query -W -f='${Version}' tiff)" ge "4.0.6-3" && echo PATCHED || echo STILL-VULNERABLE
RHEL 6 · libtiff · FIXED · libtiff-3.9.4-18.el6_8
sudo dnf upgrade --advisory=RHSA-2016:1547
rpm -q libtiff
RHEL 7 · libtiff · FIXED · libtiff-4.0.3-25.el7_2
sudo dnf upgrade --advisory=RHSA-2016:1546
rpm -q libtiff
RHEL 5 · libtiff · NO FIX YET
sudo yum update --advisory=ALAS-2016-733
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.
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-2015-8668?
libtiff: upgrade to newer than 4.0.6; vm server: downgrade or apply the listed mitigation; linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2015-8668 being exploited?
CVE-2015-8668 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-2015-8668 affect?
CVE-2015-8668 affects libtiff, vm server, linux. Severity is critical (CVSS 9.8). Heap-based buffer overflow in the PackBitsPreEncode function in tif_packbits.c in bmp2tiff in libtiff 4.0.6 and earlier allows remote attackers to execute arbitrary code or cause a denial of service via a large width field in a BMP image.
How urgent is CVE-2015-8668?
Priority 73/100. Critical severity; EPSS top 3%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist
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