# CVE-2026-54873: QUIC STREAM Fragment Metadata DoS CVE-2026-54873 is fixed in 13 products on 1 platform, first by libssl3t64 3.5.5-1ubuntu3.7, released September 29, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-54873 - Priority: High - CVSS: 7.5 (Moderate) - EPSS: 0.0072 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Sep 29, 2026 - Weakness: Allocation of Resources Without Limits or Throttling - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54873 ## Description Issue summary: QUIC process may keep memory for QUIC packet buffer for much longer period than necessary. Impact summary: Remote peer can exploit this vulnerability by sending maliciously crafted packets, making the local QUIC stack to keep the memory for packet buffers allocated. The time for which the memory remains allocated is entirely under the control of the potentially malicious remote peer. CWE: CWE-770: Allocation of Resources Without Limits or Throttling Description: To save copy operation from the packet buffer to the stream reassemble buffer the QUIC stack leaves the stream data on the packet buffer waiting to be copied to a buffer provided by the local receiving application. The QUIC stack releases a reference to the packet buffer only after the data are copied to the application buffer. This design is more efficient for legitimate data transfers but enables an attacker to allocate a lot more memory than actually required by the data kept in the receiving stream buffer. To mitigate the vulnerability, the QUIC stack now calculates and monitors memory overhead for every stream. The memory overhead for a single stream frame is calculated as a difference between the size of the whole packet that carries the stream frame and the size of the stream frame itself. The memory overhead for a single stream frame is added to the total (cumulative) memory overhead QUIC stack keeps for each stream. Once the cumulative memory overhead exceeds 64kB, the QUIC stack moves the stream frame data from the packet buffer to the stream buffer, starting with the next packet received. FIPS impact: no The FIPS module is not affected as the QUIC implementation is outside of the OpenSSL FIPS module boundary. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | libssl3t64 Ubuntu 26.04.1 LTS (resolute) | 3.5.5-1ubuntu3.7 | [libssl3t64 3.5.5-1ubuntu3.7](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libssl3t64-3.5.5-1ubuntu3.7.md) | Sep 29, 2026 | | Linux | openssl Debian 13.5 (trixie) | 3.5.7-1~deb13u3 | [DEBIAN-CVE-2026-54873](https://patchblox.com/security/data/fix/linux/debian-cve-2026-54873.md) | Sep 30, 2026 | | Linux | openssl Debian 14 | 3.6.5-1 | [DEBIAN-CVE-2026-54873](https://patchblox.com/security/data/fix/linux/debian-cve-2026-54873.md) | Sep 30, 2026 | | Linux | openssl Ubuntu 26.04.1 LTS (resolute) | 3.5.5-1ubuntu3.7 | [openssl 3.5.5-1ubuntu3.7](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-openssl-3.5.5-1ubuntu3.7.md) | Sep 29, 2026 | | Linux | openssl amzn 2023 | 1:3.5.8-1.amzn2023.0.3 | [ALAS2023-2026-3204](https://patchblox.com/security/data/fix/linux/alas2023-2026-3204.md) | Nov 7, 2026 | | Linux | openssl-debuginfo amzn 2023 | 1:3.5.8-1.amzn2023.0.3 | [ALAS2023-2026-3204](https://patchblox.com/security/data/fix/linux/alas2023-2026-3204.md) | Nov 7, 2026 | | Linux | openssl-debugsource amzn 2023 | 1:3.5.8-1.amzn2023.0.3 | [ALAS2023-2026-3204](https://patchblox.com/security/data/fix/linux/alas2023-2026-3204.md) | Nov 7, 2026 | | Linux | openssl-devel amzn 2023 | 1:3.5.8-1.amzn2023.0.3 | [ALAS2023-2026-3204](https://patchblox.com/security/data/fix/linux/alas2023-2026-3204.md) | Nov 7, 2026 | | Linux | openssl-fips-provider-latest amzn 2023 | 1:3.5.8-1.amzn2023.0.3 | [ALAS2023-2026-3204](https://patchblox.com/security/data/fix/linux/alas2023-2026-3204.md) | Nov 7, 2026 | | Linux | openssl-fips-provider-latest-debuginfo amzn 2023 | 1:3.5.8-1.amzn2023.0.3 | [ALAS2023-2026-3204](https://patchblox.com/security/data/fix/linux/alas2023-2026-3204.md) | Nov 7, 2026 | | Linux | openssl-libs amzn 2023 | 1:3.5.8-1.amzn2023.0.3 | [ALAS2023-2026-3204](https://patchblox.com/security/data/fix/linux/alas2023-2026-3204.md) | Nov 7, 2026 | | Linux | openssl-libs-debuginfo amzn 2023 | 1:3.5.8-1.amzn2023.0.3 | [ALAS2023-2026-3204](https://patchblox.com/security/data/fix/linux/alas2023-2026-3204.md) | Nov 7, 2026 | | Linux | openssl-perl amzn 2023 | 1:3.5.8-1.amzn2023.0.3 | [ALAS2023-2026-3204](https://patchblox.com/security/data/fix/linux/alas2023-2026-3204.md) | Nov 7, 2026 | | Linux | openssl-provider-legacy Ubuntu 26.04.1 LTS (resolute) | 3.5.5-1ubuntu3.7 | [openssl-provider-legacy 3.5.5-1ubuntu3.7](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-openssl-provider-legacy-3.5.5-1ubuntu3.7.md) | Sep 29, 2026 | | Linux | openssl-snapsafe-libs amzn 2023 | 1:3.5.8-1.amzn2023.0.3 | [ALAS2023-2026-3204](https://patchblox.com/security/data/fix/linux/alas2023-2026-3204.md) | Nov 7, 2026 | | Linux | openssl-snapsafe-libs-debuginfo amzn 2023 | 1:3.5.8-1.amzn2023.0.3 | [ALAS2023-2026-3204](https://patchblox.com/security/data/fix/linux/alas2023-2026-3204.md) | Nov 7, 2026 | --- Data as of 2026-11-08T00:53:09Z UTC. 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