CVE-2017-5446: An out-of-bounds read when an HTTP/2 connection to a servers sends "DATA" frames with incorrect data content

Q: How do I fix CVE-2017-5446?

debian linux: mitigate or apply the listed mitigation; enterprise linux: mitigate or apply the listed mitigation; enterprise linux desktop: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2017-5446 being exploited?

CVE-2017-5446 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2017-5446 affect?

CVE-2017-5446 affects debian linux, enterprise linux, enterprise linux desktop. Severity is critical (CVSS 9.8). An out-of-bounds read when an HTTP/2 connection to a servers sends "DATA" frames with incorrect data content. This leads to a potentially exploitable crash. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 45.9, Firefox ESR < 52

Q: How urgent is CVE-2017-5446?

Priority 71/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

This week

CRITICAL 9.8REMOTEWATCHLISTMITIGATEMITIGATEMITIGATE

CVE-2017-5446 is a critical-severity flaw (CVSS 9.8) affecting debian linux, enterprise linux, enterprise linux desktop. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An out-of-bounds read when an HTTP/2 connection to a servers sends "DATA" frames with incorrect data content. This leads to a potentially exploitable crash. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 45.9, Firefox ESR < 52.1, and Firefox < 53.

Why this priority

Critical severity
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	3.0% (top 13%)
CISA exploited list	No
Weakness	CWE-125
Published	2018-06-11
Last modified	2026-06-17

Publisher (CNA): Mozilla Corporation · Vendor: debian · redhat

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

Am I affected?

Timeline

2018-06-11 21:29 UTCPublished CVE record published
2026-06-17 01:20 UTCUpdated Record last modified

debian debian linux MITIGATE

Affected: 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

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 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 server 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 server aus MITIGATE

Affected: 7.3 · 7.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.3

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 server eus MITIGATE

Affected: 7.3 · 7.4 · 7.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.3

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 · librepo · FIXED · 1.21.3-1.fc46 · FEDORA-2026-c502136ca7 · source

sudo dnf upgrade --advisory=FEDORA-2026-c502136ca7

Debian 12 · firefox-esr · FIXED · 45.9.0esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "45.9.0esr-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · firefox-esr · FIXED · 45.9.0esr-1

sudo apt update && sudo apt install --only-upgrade firefox-esr dpkg --compare-versions "$(dpkg-query -W -f='${Version}' firefox-esr)" ge "45.9.0esr-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 6 · firefox · FIXED · firefox-52.1.0-2.el6_9

sudo dnf upgrade --advisory=RHSA-2017:1104 rpm -q firefox

RHEL 6 · thunderbird · FIXED · thunderbird-52.1.0-1.el6_9

sudo dnf upgrade --advisory=RHSA-2017:1201 rpm -q thunderbird

RHEL 7 · firefox · FIXED · firefox-52.1.0-2.el7_3

sudo dnf upgrade --advisory=RHSA-2017:1106 rpm -q firefox

RHEL 7 · thunderbird · FIXED · thunderbird-52.1.0-1.el7_3

sudo dnf upgrade --advisory=RHSA-2017:1201 rpm -q thunderbird

RHEL 5 · firefox · DEFERRED

Public exploits and detection

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

Write-up: www.mozilla.org/security/advisories/mfsa2017-12/

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-2017-5446?

debian linux: mitigate or apply the listed mitigation; enterprise linux: mitigate or apply the listed mitigation; enterprise linux desktop: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-5446 being exploited?

CVE-2017-5446 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-2017-5446 affect?

CVE-2017-5446 affects debian linux, enterprise linux, enterprise linux desktop. Severity is critical (CVSS 9.8). An out-of-bounds read when an HTTP/2 connection to a servers sends "DATA" frames with incorrect data content. This leads to a potentially exploitable crash. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 45.9, Firefox ESR < 52

How urgent is CVE-2017-5446?

Priority 71/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities · Mozilla Firefox vulnerabilities · Mozilla Thunderbird vulnerabilities

Related CVEs

CVE-2026-111497 CRITICAL 9.8 EXPLOITED UPGRADE UPGRADE Google Brotli Unchecked Return Value Vulnerability
CVE-2025-38728 CRITICAL 9.1 UPGRADE MITIGATE In the Linux kernel, the following vulnerability has been resolved: smb3: fix for slab out of bounds on mount
CVE-2025-38204 HIGH 7.8 UPGRADE MITIGATE In the Linux kernel, the following vulnerability has been resolved: jfs: fix array-index-out-of-bounds read i
CVE-2024-26889 MEDIUM 5.5 UPGRADE MITIGATE In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_core: Fix possible buffer
CVE-2023-2462 MEDIUM 4.3 UPGRADE MITIGATE Inappropriate implementation in Prompts in Google Chrome prior to 113.0.5672.63 allowed a remote attacker to o

References

← Back to latest CVEs