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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

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

Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

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 100.0%, 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 October 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🦀

🦀 crates.io🐹 Go📦 npm.NET NuGet🐍 PyPI

CISA KEV · ACTIVELY EXPLOITED

HIGH severity

CVE-2023-4863 — libwebp-sys2

HIGHFix: webmproject/libwebp@902bc91

CVE-2023-4863 is a high-severity (CVSS 8.8) Out-of-bounds Write vulnerability in libwebp-sys2. It is in CISA's Known Exploited Vulnerabilities catalog (added 2023-09-13) — treat it as actively exploited and patch now. A fix is available for libwebp-sys2 — see the affected versions and patch details below.

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

Oct 21, 2026

Affected

19 pkgs

Patched

19 / 19

Exploits

26 known

Exploitation data as of Oct 23, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2023-09-13. Federal agencies were required to remediate by 2023-10-04.
A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2023-4863.

EPSS Exploitation Probability

via FIRST.org ↗

100.0%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2023-4863 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).

Where this sits among everything scored

Of 395,249 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

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`cargo update -p libwebp-sys2 --precise 0.1.8`
🦀crates.io	`libwebp-sys`	all versions	0.9.3`cargo update -p libwebp-sys --precise 0.9.3`
🦀crates.io	`webp`	all versions	0.2.6`cargo update -p webp --precise 0.2.6`
🐹Go	`github.com/chai2010/webp`	≥ 1.1.2&&< 1.4.0	1.4.0`go get github.com/chai2010/webp@v1.4.0`
🐹Go	`github.com/chai2010/webp`	all versions	0.0.0-20250406010349-76805d5a8860`go get github.com/chai2010/webp@v0.0.0-20250406010349-76805d5a8860`
🐹Go	`github.com/chai2010/webp`	≥ 0.0.0&&< 1.1.2-0.20250406010349-76805d5a8860	1.1.2-0.20250406010349-76805d5a8860`go get github.com/chai2010/webp@v1.1.2-0.20250406010349-76805d5a8860`

Affected Products

12 products · 20 configurations

Application

honeyviewbandisoft

< 5.51

range

Application

seequent leapfrogbentley

< 2023.2

range

debian linuxdebian

3 versions

10.011.012.0

fedorafedoraproject

3 versions

373839

Application

chromegoogle

< 116.0.5845.187

range

Application

edge chromiummicrosoft

< 116.0.1938.81

range

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.