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CVE-2026-63075— QUIC ACK-only Packet Retention Can Cause Memory Exhaustion

Quick assessment

Affected
OpenSSL OpenSSL
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

OpenSSL是OpenSSL团队开源的一个提供安全通信加密功能的软件库。 OpenSSL 4.0.0至4.0.2之前版本、3.6.0至3.6.4之前版本、3.5.0至3.5.8之前版本和3.4.0至3.4.7之前版本存在资源管理错误漏洞，该漏洞源于处理QUIC流量时未限制资源分配，保留ACK-only数据包元数据，可能导致远程攻击者造成内存耗尽，引发拒绝服务。

AI Predicted 7.5 Difficulty: Easy EPSS 0.78% · P55

Affected Version Matrix 4

VendorProduct Version RangeStatus
OpenSSL OpenSSL 4.0.0< 4.0.2 affected
3.6.0< 3.6.4 affected
3.5.0< 3.5.8 affected
3.4.0< 3.4.7 affected
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I. Basic Information for CVE-2026-63075

Vulnerability Information
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Vulnerability Title
QUIC ACK-only Packet Retention Can Cause Memory Exhaustion
Source: CVE Program / CVE List V5
Vulnerability Description
Issue summary: When OpenSSL processes QUIC traffic from a peer that repeatedly sends ack-eliciting packets while not acknowledging ACK-only responses, the QUIC stack can retain ACK-only packet metadata for the lifetime of the connection. Impact summary: A remote peer that can complete a QUIC handshake can cause connection-scoped memory growth which may lead to Denial of Service through memory exhaustion, especially with sustained traffic or many concurrent QUIC connections. CWE: CWE-770: Allocation of Resources Without Limits or Throttling Description: When the OpenSSL QUIC stack sends an ACK-only packet, there is no requirement by the QUIC protocol that the peer will acknowledge that ACK-only packet (i.e. it is itself not ack-eliciting). However, the OpenSSL implementation stores the metadata about the ACK frames regardless. In and of itself that's ok, but if a malicious peer establishes a connection, and then drives the connection such that ACK-only packets are forced from the OpenSSL implementation peer (i.e., by sending numerous PING frames), and then withholding any subsequent acks for ack-eliciting data, like legitimate data, said malicious peer can force inappropriate memory growth on the OpenSSL peer, potentially leading to a Denial of Service. The fix is to ensure that we account for the transmission of the ACK-only packet in the packet histories high and low watermark without actually storing the ACK-only packet metadata itself. FIPS impact: no The OpenSSL FIPS module is not affected as the QUIC code is outside the FIPS module boundary.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5
Vulnerability Title
OpenSSL 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
OpenSSL是OpenSSL团队开源的一个提供安全通信加密功能的软件库。 OpenSSL 4.0.0至4.0.2之前版本、3.6.0至3.6.4之前版本、3.5.0至3.5.8之前版本和3.4.0至3.4.7之前版本存在资源管理错误漏洞，该漏洞源于处理QUIC流量时未限制资源分配，保留ACK-only数据包元数据，可能导致远程攻击者造成内存耗尽，引发拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
OpenSSL OpenSSL 4.0.0 ~ 4.0.2 -

II. Public POCs for CVE-2026-63075

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III. Intelligence Information for CVE-2026-63075

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Patches & Fixes for CVE-2026-63075 (4)

Vendor Advisories for CVE-2026-63075 (1)

Same Patch Batch · OpenSSL · 2026-08-25 · 9 CVEs total

CVE-2026-75803 AEAD Forgeries with Empty Ciphertext When Using EVP_Cipher()
CVE-2026-18798 QUIC Server May Trigger Double Free When Processing INITIAL Packet
CVE-2026-54874 Excessive Memory Use Buffering DTLS Records for a Future Epoch
CVE-2026-63074 CMP Indefinite Cache Growth of ExtraCerts
CVE-2026-63072 Heap Buffer Overflow in CMS Key Unwrapping
CVE-2026-63073 Untrusted Sender DN Used as Format String in CMP Response Validation
CVE-2026-63076 Invalid Pointer Dereference in CMP Server via Crafted protectionAlg
CVE-2026-14457 RPK Server Signature Algorithm Selection Can Dereference a Missing Certificate

IV. Related Vulnerabilities

Same product: OpenSSL
Same vendor: OpenSSL
Same weakness: CWE-770

V. Comments for CVE-2026-63075

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