Medium · CVSS 4.8CVE-2026-12549

Libsoup: incomplete fix for cve-2026-2443: range suffix overflow in libsoup soupserverCVE-2026-12549

Answer in brief

CVE-2026-12549 records a Medium severity (CVSS 4.8) vulnerability in Libsoup: incomplete fix for cve-2026-2443: range suffix overflow in libsoup soupserver. The current sources do not mark it as known exploited. The current feed maps Red Hat/libsoup (generic), Red Hat/libsoup3 (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jun 22, 2026Updated Jul 8, 2026Source checked Nov 3, 2026First seen by HOL Jun 22, 2026Material review Jul 8, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 4.8
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Not reported

Why this deserves its current priority

CVSS is 4.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Red Hat/libsoup (generic), Red Hat/libsoup3 (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Red Hat/libsoupgeneric	*	Not reported
Red Hat/libsoup3generic	*	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Red Hat/libsoup, Red Hat/libsoup3.
Review the reported fix. Source-reported workaround: To mitigate this issue, applications utilizing libsoup's WebSocket support should ensure that the `max_incoming_payload_size` is explicitly set to a non-zero value. This prevents the library from processing WebSocket frames with an unset or zero maximum payload size, which can lead to out-of-bounds reads. Consult application-specific documentation for configuring libsoup parameters.

Evidence timeline and material changes

Published upstream
Jun 22, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Jul 8, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Jun 22, 2026

Sources and claim methodology

Upstream source description

The fix for CVE-2026-2443 was regressed by a subsequent rework commit that replaced specific overflow checks with a general signed comparison. When a client sends a Range request with a suffix length exceeding the content size, the resulting negative start value is not properly clamped, leading to malformed HTTP 206 responses and log flooding.

Quoted source text, attributed separately from HOL analysis.