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curl CVE-2026-11352

| EUVDEUVD-2026-41498 HIGH
Loop with Unreachable Exit Condition (Infinite Loop) (CWE-835)
7.5
CVSS 3.1 · Vendor
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Severity by source

Vendor (CNA) PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
6.5 HIGH

Network QUIC transport with trivial empty-datagram trigger (AV:N/AC:L), no server-side auth (PR:N); availability-only livelock (A:H), no confidentiality/integrity impact, scope unchanged.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
HIGH
qualitative
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (CNA).

CVSS VectorVendor

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

9
Analysis Updated
Jul 06, 2026 - 21:51 vuln.today
v7 (cvss_changed)
Analysis Updated
Jul 06, 2026 - 21:50 vuln.today
v6 (cvss_changed)
Analysis Updated
Jul 06, 2026 - 21:49 vuln.today
v5 (cvss_changed)
Analysis Updated
Jul 06, 2026 - 21:49 vuln.today
v4 (cvss_changed)
Analysis Updated
Jul 06, 2026 - 21:48 vuln.today
v3 (cvss_changed)
Analysis Updated
Jul 06, 2026 - 21:45 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Jul 06, 2026 - 19:22 vuln.today
cvss_changed
CVSS changed
Jul 06, 2026 - 19:22 NVD
7.5 (HIGH)
Analysis Generated
Jun 24, 2026 - 18:29 vuln.today

Description PRE-NVD

Disclosed via oss-security. NVD scoring and full description are pending.

AnalysisAI

Remote denial of service in curl and libcurl (versions 8.18.0 through 8.20.0) lets a malicious or compromised HTTP/3 server indefinitely stall a connecting client. The flaw lives in curl's QUIC UDP receive path, where zero-length UDP datagrams are discarded before they are counted against the per-call packet budget, so a peer that streams a continuous flood of empty datagrams keeps the receive loop spinning without ever making progress. There is no public exploit identified at time of analysis, EPSS risk is low (0.28%, 20th percentile), and impact is availability-only (no data compromise).

Technical ContextAI

curl/libcurl is one of the most widely embedded HTTP client libraries in existence, and this issue is specific to its HTTP/3 support, which runs over the QUIC transport on top of UDP rather than TCP. QUIC receive handling reads datagrams in batches bounded by a per-call packet budget to keep a single call from monopolizing the event loop. The helper function that feeds this loop discards zero-length UDP datagrams before incrementing the budget counter, so empty datagrams never count toward the limit. A connected QUIC peer can therefore stream an unbounded sequence of empty datagrams and the loop never reaches its exit condition, producing a livelock/hang. No CWE was assigned in the input, but the root cause is an improper loop-termination / uncontrolled-resource-consumption condition (CWE-835 uncontrolled loop / CWE-400 class). The EUVD record (EUVD-2026-41498) enumerates the affected curl builds.

RemediationAI

No vendor-released patch version is identified in the provided data; the curl advisory at https://curl.se/docs/CVE-2026-11352.html is the authoritative source for the exact fixed release (curl's practice is to fix in the next tagged release above the affected line, but the specific version is not confirmed from the input and should not be assumed). Upgrade curl/libcurl to that fixed release once confirmed from the advisory. As an interim compensating control, disable or avoid HTTP/3 for affected clients - for the curl CLI, do not pass --http3 / --http3-only and let it fall back to HTTP/2 or HTTP/1.1 (trade-off: loss of QUIC latency/performance benefits); for libcurl applications, avoid setting CURLOPT_HTTP_VERSION to CURL_HTTP_VERSION_3, or build libcurl without an HTTP/3 backend. Additionally restrict HTTP/3 clients to trusted servers and monitor/limit connection duration, since the attack requires the client to remain connected to a hostile QUIC peer. Review the oss-security thread (https://seclists.org/oss-sec/2026/q2/1012) for coordinated fix details.

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
SLES15-SP5-CHOST-BYOS-SAP-CCloud Not-Affected
SLES15-SP6-CHOST-BYOS Not-Affected
SLES15-SP6-CHOST-BYOS-Aliyun Not-Affected
SLES15-SP6-CHOST-BYOS-Azure Not-Affected
SLES15-SP6-CHOST-BYOS-EC2 Not-Affected

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CVE-2026-11352 vulnerability details – vuln.today

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