CVE-2015-0823: Multiple use-after-free vulnerabilities in OpenType Sanitiser, as used in Mozilla Firefox before 36.0, might a

Q: How do I fix CVE-2015-0823?

ubuntu linux: mitigate or apply the listed mitigation; opentype sanitiser: mitigate or apply the listed mitigation; firefox: upgrade to newer than 35.0.1. Exact commands for each OS are on this page.

Q: Is CVE-2015-0823 being exploited?

CVE-2015-0823 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-2015-0823 affect?

CVE-2015-0823 affects ubuntu linux, opentype sanitiser, firefox. Severity is high (CVSS 7.5). Multiple use-after-free vulnerabilities in OpenType Sanitiser, as used in Mozilla Firefox before 36.0, might allow remote attackers to trigger problematic Developer Console information or possibly have unspecified other impact by leveraging

Q: How urgent is CVE-2015-0823?

Priority 54/100. High severity; EPSS top 10%: very likely to be exploited; On your watchlist

This month

HIGH 7.5WATCHLISTMITIGATEMITIGATEUPGRADE

CVE-2015-0823 is a high-severity flaw (CVSS 7.5) affecting ubuntu linux, opentype sanitiser, firefox. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Multiple use-after-free vulnerabilities in OpenType Sanitiser, as used in Mozilla Firefox before 36.0, might allow remote attackers to trigger problematic Developer Console information or possibly have unspecified other impact by leveraging incorrect macro expansion, related to the ots::ots_gasp_parse function.

Why this priority

High severity
EPSS top 10%: very likely to be exploited
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	3.9% (top 10%)
CISA exploited list	No
Published	2015-02-25
Last modified	2026-06-17

Publisher (CNA): Mozilla Corporation · Vendor: canonical · mozilla · opensuse · opentype sanitiser project

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

Am I affected?

Timeline

2015-02-25 11:59 UTCPublished CVE record published
2026-06-17 00:20 UTCUpdated Record last modified

canonical ubuntu linux MITIGATE

Affected: 12.04 · 14.04 · 14.10

Fixed in: no fixed release known

Safe to downgrade to: a release before 12.04

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.

opentype sanitiser project opentype sanitiser 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 opentype-sanitiser || rpm -q opentype-sanitiser || opentype-sanitiser --version

No fixed or unaffected release known

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

mozilla firefox UPGRADE

Affected: <= 35.0.1 · 0.1 · 0.2 · 0.3 · 0.4 · 0.5 · 0.6 · 0.6.1

Fixed in: newer than 35.0.1

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 35.0.1 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade firefox

Note

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

opensuse opensuse MITIGATE

Affected: 13.1 · 13.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 13.1

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.

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-2015-0823?

ubuntu linux: mitigate or apply the listed mitigation; opentype sanitiser: mitigate or apply the listed mitigation; firefox: upgrade to newer than 35.0.1. Exact commands for each OS are on this page.

Is CVE-2015-0823 being exploited?

CVE-2015-0823 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-2015-0823 affect?

CVE-2015-0823 affects ubuntu linux, opentype sanitiser, firefox. Severity is high (CVSS 7.5). Multiple use-after-free vulnerabilities in OpenType Sanitiser, as used in Mozilla Firefox before 36.0, might allow remote attackers to trigger problematic Developer Console information or possibly have unspecified other impact by leveraging

How urgent is CVE-2015-0823?

Priority 54/100. High severity; EPSS top 10%: very likely to be exploited; On your watchlist

Software pages

Ubuntu vulnerabilities · Mozilla Firefox vulnerabilities

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References

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