SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2017-5447

An out-of-bounds read during the processing of glyph widths during text layout.

EXPLOIT ✓CRITICAL 9.1EPSS 17.0%

Does this matter?

EPSS puts the probability of exploitation in the next 30 days at 17.0%, higher than 97% of all known CVEs. Patch or mitigate before the next change window.

Description

An out-of-bounds read during the processing of glyph widths during text layout. This results in a potentially exploitable crash and could allow an attacker to read otherwise inaccessible memory. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 45.9, Firefox ESR < 52.1, and Firefox < 53.

CVSS 3.0
9.1 CRITICALCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
EPSS
16.98% probability · 97th percentile
Public exploits
1 in Exploit-DB · verified · first 25 May 2017
CISA KEV
Not listed
Weakness
CWE-416
Affected
debian/debian linux · redhat/enterprise linux · redhat/enterprise linux desktop · redhat/enterprise linux server · redhat/enterprise linux server aus · redhat/enterprise linux server eus · redhat/enterprise linux workstation · mozilla/firefox · mozilla/thunderbird
Source
security@mozilla.org
EPSS trend
0%10%20%21 September 2026: 12.41%22 September 2026: 17.31%27 October 2026: 16.98%21 September 202627 October 2026

EPSS moved from 12.4% on 21 September 2026 to 17.0% on 27 October 2026, peaking at 17.3% on 22 September 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.

Public exploits (1)

Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.

EDB-IDTitleTypePublishedVerified
EDB-42071source ↗Mozilla Firefox < 53 - 'gfxTextRun' Out-of-Bounds Readmultiple · Google Security Researchdos25 May 2017yes

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.