CVE-2026-54873: Issue summary: QUIC process may keep memory for QUIC packet buffer for much longer period than necessary. Imp

Q: How do I fix CVE-2026-54873?

openssl: upgrade to 3.4.8, 3.5.9, 3.6.5, 4.0.3. Exact commands for each OS are on this page.

Q: Is CVE-2026-54873 being exploited?

CVE-2026-54873 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-54873 affect?

CVE-2026-54873 affects openssl. Severity is high (CVSS 7.5). 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 kee

Q: How urgent is CVE-2026-54873?

Priority 49/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

This month

HIGH 7.5REMOTEWATCHLISTUPGRADE

CVE-2026-54873 is a high-severity flaw (CVSS 7.5) affecting openssl. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 47%)
CISA exploited list	No
Weakness	CWE-770
Published	2026-09-29
Last modified	2026-10-08

Publisher (CNA): OpenSSL Software Foundation · Vendor: openssl

Last updated 2026-10-08 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-29 16:17 UTCPublished CVE record published
2026-10-08 01:19 UTCUpdated Record last modified

openssl openssl UPGRADE

Affected: >= 3.4.0 and < 3.4.8 · >= 3.5.0 and < 3.5.9 · >= 3.6.0 and < 3.6.5 · >= 4.0.0 and < 4.0.3

Fixed in: 3.4.8, 3.5.9, 3.6.5, 4.0.3

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy openssl || rpm -q openssl || openssl --version

2. UPGRADE to 3.4.8 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade openssl

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade openssl

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Advisories and coverage

Official advisories

Amazon Linux 2023 ALAS: ALAS2023-2026-3204 (important): openssl 2026-10-12
OpenSSL Vulnerabilities: OpenSSL 4.0.3 2026-09-29
OpenSSL Vulnerabilities: OpenSSL 3.6.5 2026-09-29
OpenSSL Vulnerabilities: OpenSSL 3.5.9 2026-09-29
OpenSSL Vulnerabilities: OpenSSL 3.4.8 2026-09-29

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-54873?

openssl: upgrade to 3.4.8, 3.5.9, 3.6.5, 4.0.3. Exact commands for each OS are on this page.

Is CVE-2026-54873 being exploited?

CVE-2026-54873 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-54873 affect?

CVE-2026-54873 affects openssl. Severity is high (CVSS 7.5). 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 kee

How urgent is CVE-2026-54873?

Priority 49/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

OpenSSL vulnerabilities

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References

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