CVE-2026-63073: Issue summary: OpenSSL CMP response validation passed an unexpected response sender distinguished name directl

Q: How do I fix CVE-2026-63073?

openssl: upgrade to 3.4.7, 3.5.8, 3.6.4, 4.0.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-63073 being exploited?

CVE-2026-63073 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-2026-63073 affect?

CVE-2026-63073 affects openssl. Severity is critical (CVSS 9.8). Issue summary: OpenSSL CMP response validation passed an unexpected response sender distinguished name directly as the format string to `ERR_raise_data()`. Impact summary: A malicious or intercepted CMP endpoint can crash a CMP client that

Q: How urgent is CVE-2026-63073?

Priority 64/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADE

CVE-2026-63073 is a critical-severity flaw (CVSS 9.8) affecting openssl. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Issue summary: OpenSSL CMP response validation passed an unexpected response sender distinguished name directly as the format string to `ERR_raise_data()`. Impact summary: A malicious or intercepted CMP endpoint can crash a CMP client that enforces an expected sender or uses a pinned server certificate whose subject becomes the default expected sender. CWE: CWE-134 (Use of Externally-Controlled Format String) Description: When validating a rec

Why this priority

Critical severity
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.2% (top 33%)
CISA exploited list	No
Weakness	CWE-134
Published	2026-08-25
Last modified	2026-09-11

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

Last updated 2026-09-11 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-25 13:19 UTCPublished CVE record published
2026-09-11 21:16 UTCUpdated Record last modified

openssl openssl UPGRADE

Affected: >= 3.4.0 and < 3.4.7 · >= 3.5.0 and < 3.5.8 · >= 3.6.0 and < 3.6.4 · >= 4.0.0 and < 4.0.2

Fixed in: 3.4.7, 3.5.8, 3.6.4, 4.0.2

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 3.4.7 (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.

Exact fixes by distribution

Debian 12 · openssl · NOT AFFECTED

Debian 13 · openssl · FIXED · 3.5.7-1~deb13u2

sudo apt update && sudo apt install --only-upgrade openssl dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssl)" ge "3.5.7-1~deb13u2" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · openssl · FIXED · openssl-3.5.8-1.el10_2

sudo dnf upgrade --advisory=RHSA-2026:67154 rpm -q openssl

RHEL 9 · openssl · FIXED · openssl-3.5.8-1.el9_8

sudo dnf upgrade --advisory=RHSA-2026:67165 rpm -q openssl

RHEL 10 · edk2 · DEFERRED

RHEL 10 · shim · NOT AFFECTED

RHEL 10 · shim-unsigned-aarch64 · NOT AFFECTED

Alpine 3.21 · openssl · FIXED · openssl-3.3.7-r1

apk add --upgrade openssl apk info -v openssl

Alpine 3.22 · openssl · FIXED · openssl-3.5.8-r0

apk add --upgrade openssl apk info -v openssl

Alpine 3.23 · openssl · FIXED · openssl-3.5.8-r0

apk add --upgrade openssl apk info -v openssl

Alpine 3.24 · openssl · FIXED · openssl-3.5.8-r0

apk add --upgrade openssl apk info -v openssl

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-2136 · source

sudo dnf update --advisory=ALAS2023-2026-2136

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-2026-63073?

openssl: upgrade to 3.4.7, 3.5.8, 3.6.4, 4.0.2. Exact commands for each OS are on this page.

Is CVE-2026-63073 being exploited?

CVE-2026-63073 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-2026-63073 affect?

CVE-2026-63073 affects openssl. Severity is critical (CVSS 9.8). Issue summary: OpenSSL CMP response validation passed an unexpected response sender distinguished name directly as the format string to `ERR_raise_data()`. Impact summary: A malicious or intercepted CMP endpoint can crash a CMP client that

How urgent is CVE-2026-63073?

Priority 64/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

Software pages

OpenSSL vulnerabilities

Related CVEs

CVE-2026-84784 HIGH 7.5 UPGRADE Issue summary: A malicious remote peer may flood the local QUIC stack with NEW_CONNECTION_ID frames by avoidin
CVE-2026-84783 HIGH 7.5 UPGRADE Issue summary: The first concurrent use of the same X.509 certificate by several threads may cause its cached
CVE-2026-84782 HIGH 8.2 UPGRADE Issue summary: The DTLS retransmission logic does not correctly handle a handshake message write that is suspe
CVE-2026-77696 LOW 3.7 UPGRADE Issue summary: SM2 signature generation uses non-constant-time arithmetic on secret values, forming a timing s
CVE-2026-75806 MEDIUM 5.3 UPGRADE Issue summary: An established DTLS 1.2 association using an AEAD cipher suite can be terminated by a single un

References

← Back to latest CVEs