CVE-2024-53863

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 0.6%, top 54% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
9.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 9.1Exploit: NoneExposed: 0

A fix is available — apply it.

Synapse is an open-source Matrix homeserver. In Synapse versions before 1.120.1, enabling the dynamic_thumbnails option or processing a specially crafted request could trigger the decoding and thumbnail generation of uncommon image formats, potentially invoking external tools like Ghostscript for processing. This significantly expands the attack surface in a historically vulnerable area, presenting a risk that far outweighs the benefit, particularly since these formats are rarely used on the open web or within the Matrix ecosystem. Synapse 1.120.1 addresses the issue by restricting thumbnail generation to images in the following widely used formats: PNG, JPEG, GIF, and WebP. This vulnerability is fixed in 1.120.1.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
56(Track)
EG Risk 56/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity91% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
46.2%
KEV
Not listed

Published

December 3, 2024

Last Modified

August 26, 2025

Advisory Details (1)

Auto-updated Jul 19, 2026
Patch available. Sources: github.
github Patch Available

Synapse can be forced to thumbnail unexpected file formats, invoking potentially untrustworthy decoders · Advisory · element-hq/synapse · GitHub

https://github.com/element-hq/synapse/security/advisories/GHSA-vp6v-whfm-rv3g

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntumatrix-synapse (1.53.0-1ubuntu0.1~esm2) @ jammy2026-05-23ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
matrix-synapse0.33.5 ... 1.99.0rc1 (415 versions)1.120.1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 10× in last 7d / 44× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 101 total refreshes for this CVE.

  1. 2026-07-23 02:44 UTCEG score recompute
  2. 2026-07-22 14:07 UTCEPSS rescore
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  44. 2026-06-08 05:28 UTCOSV refresh
  45. 2026-06-07 15:24 UTCEPSS rescore
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  75. 2026-05-23 17:04 UTCEG score recompute

Frequently asked(5)

What is CVE-2024-53863?
CVE-2024-53863 is a critical vulnerability published on December 3, 2024. Synapse is an open-source Matrix homeserver. In Synapse versions before 1.120.1, enabling the dynamic_thumbnails option or processing a specially crafted request could trigger the decoding and thumbnail generation of uncommon image formats, potentially invoking external tools like Ghostscript for…
When was CVE-2024-53863 disclosed?
CVE-2024-53863 was first published in the National Vulnerability Database on December 3, 2024, with the most recent update on August 26, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2024-53863 actively exploited?
CVE-2024-53863 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 46.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2024-53863?
CVE-2024-53863 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2024-53863?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2024-53863, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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