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    2 vulnerabilities by ngtcp2

    CVE-2026-40170 (GCVE-0-2026-40170)

    Vulnerability from cvelistv5 – Published: 2026-04-16 21:34 – Updated: 2026-04-20 15:00
    VLAI
    Title
    ngtcp2 has a qlog transport parameter serialization stack buffer overflow
    Summary
    ngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2_qlog_parameters_set_transport_params() serializes peer transport parameters into a fixed 1024-byte stack buffer without bounds checking. When qlog is enabled, a remote peer can send sufficiently large transport parameters during the QUIC handshake to cause writes beyond the buffer boundary, resulting in a stack buffer overflow. This affects deployments that enable the qlog callback and process untrusted peer transport parameters. This issue has been fixed in version 1.22.1. If developers are unable to immediately upgrade, they can disable the qlog on client.
    Severity
    7.5 (High)
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
    SSVC
    Exploitation: poc Automatable: yes Technical Impact: partial
    CISA Coordinator (v2.0.3)
    CWE
    • CWE-121 - Stack-based Buffer Overflow
    Assigner
    References
    Impacted products
    Vendor Product Version
    ngtcp2 ngtcp2 Affected: < 1.22.1
    		Create a notification for this product.
    Show details on NVD website
    To clipboard 

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                "timestamp": "2026-04-17T14:52:12.292330Z",
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            "url": "https://github.com/ngtcp2/ngtcp2/security/advisories/GHSA-f523-465f-8c8f"
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    CVE-2024-52811 (GCVE-0-2024-52811)

    Vulnerability from cvelistv5 – Published: 2024-11-25 18:55 – Updated: 2024-11-25 20:21
    VLAI
    Title
    Acks not validated before logged to qlog leads to buffer overflow in ngtcp2
    Summary
    The ngtcp2 project is an effort to implement IETF QUIC protocol in C. In affected versions acks are not validated before being written to the qlog leading to a buffer overflow. In `ngtcp2_conn::conn_recv_pkt` for an ACK, there was new logic that got added to skip `conn_recv_ack` if an ack has already been processed in the payload. However, this causes us to also skip `ngtcp2_pkt_validate_ack`. The ack which was skipped still got written to qlog. The bug occurs in `ngtcp2_qlog::write_ack_frame`. It is now possible to reach this code with an invalid ack, suppose `largest_ack=0` and `first_ack_range=15`. Subtracting `largest_ack - first_ack_range` will lead to an integer underflow which is 20 chars long. However, the ngtcp2 qlog code assumes the number written is a signed integer and only accounts for 19 characters of overhead (see `NGTCP2_QLOG_ACK_FRAME_RANGE_OVERHEAD`). Therefore, we overwrite the buffer causing a heap overflow. This is high priority and could potentially impact many users if they enable qlog. qlog is disabled by default. Due to its overhead, it is most likely used for debugging purpose, but the actual use is unknown. ngtcp2 v1.9.1 fixes the bug and users are advised to upgrade. Users unable to upgrade should not turn on qlog.
    Severity
    8.2 (High)
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
    SSVC
    Exploitation: none Automatable: yes Technical Impact: partial
    CISA Coordinator (v2.0.3)
    CWE
    • CWE-670 - Always-Incorrect Control Flow Implementation
    Assigner
    References
    Impacted products
    Vendor Product Version
    ngtcp2 ngtcp2 Affected: = 1.9.0
    		Create a notification for this product.
    ngtcp2 ngtcp2 Affected: 1.9.0
        cpe:2.3:a:ngtcp2:ngtcp2:1.9.0:*:*:*:*:*:*:*
    		 Create a notification for this product.
    Show details on NVD website
    To clipboard 

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