Google Chromium WebP Heap-Based Buffer Overflow Vulnerability

Heap buffer overflow in libwebp in Google Chrome prior to 116.0.5845.187 and libwebp 1.3.2 allowed a remote attacker to perform an out of bounds memory write via a crafted HTML page. (Chromium security severity: Critical)

CheckOps priority index

8.9/10 Patch within 24 h

Severity8.8

Probability10.0

Exploitation4/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 99.98% higher than 99.98% of CVEs

CVSS 3.1 8.8 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:

Exploited for 1,147 days 13 Sept 2023

CISA due date 04 Oct 2023 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 4 / 5

KEV catalog (CISA)13 Sept 2023
Exploited in EUVD (ENISA)13 Sept 2023
Used by ransomwareno
EPSS above 10 %99.98%
No account, over the networkyes

What to do

Fix

Update to a fixed version: 1.2.4-0.2+deb12u1 1.2.4-0.3 10.0.1

CISA guidance: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Affected products

libwebpChromeChromium WebP

Affected versions

1.3.2 <1.3.2
116.0.5845.187 <116.0.5845.187

Weaknesses (CWE)

CWE-787

Open source packages OSV

libwebpDebian:12 · CVE-2023-4863
fixed in 1.2.4-0.2+deb12u1
libwebpDebian:13 · CVE-2023-4863
fixed in 1.2.4-0.3
pillowPyPI · PYSEC-2026-1794
fixed in 10.0.1
pillowPyPI · GHSA-j7hp-h8jx-5ppr
fixed in 10.0.1

Timeline

12 Sept 2023
Published
13 Sept 2023
Exploitation reported (ENISA)
13 Sept 2023
Added to the KEV catalog
04 Oct 2023
CISA remediation due date
26 Sept 2026
EPSS peak: 99.98%

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CVE-2026-85046Google Chromium V8 Type Confusion Vulnerability
5.4 · Actively exploited
CVE-2026-11645Google Chromium V8 Out-of-Bounds Read and Write Vulnerability
5.4 · Actively exploited
CVE-2026-5281Google Dawn Use-After-Free Vulnerability
6.3 · Background exploitation