How severe is CVE-2023-4863?

CVE-2023-4863 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2023-4863?

CVE-2023-4863 affects the following packages: libwebp-sys2 (crates.io), libwebp-sys (crates.io), webp (crates.io), github.com/chai2010/webp (Go), github.com/chai2010/webp (Go), github.com/chai2010/webp (Go), electron (npm), electron (npm), and 11 more. Ecosystems affected: crates.io, Go, npm, NuGet, PyPI.

How do I fix CVE-2023-4863?

Update libwebp-sys2 to 0.1.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-4863 is resolved across your whole dependency graph.

How do I detect CVE-2023-4863 in my crates.io, Go, npm, NuGet, PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for libwebp-sys2. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2023-4863 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2023-4863?

O3 pinpoints whether CVE-2023-4863 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2023-4863 actively exploited in the wild?

Yes. There are 26 known exploit references for CVE-2023-4863, including 17 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2023-4863?

CVE-2023-4863 has an EPSS (Exploit Prediction Scoring System) score of 99.7%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2023-4863 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2023-4863 (Google Chromium WebP Heap-Based Buffer Overflow Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2023-09-13. CISA required all US federal civilian agencies to remediate this vulnerability by 2023-10-04. The required action was: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2023-4863?

CVE-2023-4863 is classified as Out-of-bounds Write (CWE-787). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2023-4863 published, and has it been updated?

CVE-2023-4863 was published on September 12, 2023 and was last updated on July 22, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2023-09-13 — agencies required to remediate by 2023-10-04

🦀 crates.io🐹 Go📦 npm.NET NuGet🐍 PyPI

CVE-2023-4863

HIGH

libwebp: OOB write in BuildHuffmanTable

Also known asA-299477569ASB-A-299477569CVE-2023-5129 GHSA-j7hp-h8jx-5pprPYSEC-2026-1794RUSTSEC-2023-0060

Published

Sep 12, 2023

Updated

Jul 22, 2026

Affected

19 pkgs

Patched

19 / 19

Exploits

26 known

EPSS Exploitation Probability

via FIRST.org ↗

99.7%probability of exploitation in next 30 days

Very High Risk100th percentile-0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

19 pkgs affected

🦀libwebp-sys2🦀libwebp-sys🦀webp🐹github.com/chai2010/webp🐹github.com/chai2010/webp🐹github.com/chai2010/webp📦electron📦electron+11 more

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

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)

Affected Packages

19 total 19 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`libwebp-sys2`	all versions	0.1.8
🦀crates.io	`libwebp-sys`	all versions	0.9.3
🦀crates.io	`webp`	all versions	0.2.6
🐹Go	`github.com/chai2010/webp`	≥ 1.1.2&&< 1.4.0	1.4.0
🐹Go	`github.com/chai2010/webp`	all versions	0.0.0-20250406010349-76805d5a8860
🐹Go	`github.com/chai2010/webp`	≥ 0.0.0&&< 1.1.2-0.20250406010349-76805d5a8860	1.1.2-0.20250406010349-76805d5a8860

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.