CVE-2026-63074: CMP Indefinite Cache Growth of ExtraCerts
Noroxi assessment
Priority: Monitor (action score 23/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.58% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
- Fixed version: OpenSSL OpenSSL 3.0.22, 3.4.7, 3.5.8; azl3 edk2 20240524git3e722403cd16-18 on Azure Linux 3.0 20240524git3e722403cd16-19; azl3 edk2 20240524git3e722403cd16-20 on Azure Linux 3.0 20240524git3e722403cd16-19.
Low priority for now. Upgrade to OpenSSL OpenSSL 3.0.22, 3.4.7, 3.5.8; azl3 edk2 20240524git3e722403cd16-18 on Azure Linux 3.0 20240524git3e722403cd16-19; azl3 edk2 20240524git3e722403cd16-20 on Azure Linux 3.0 20240524git3e722403cd16-19 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
Issue summary: The OpenSSL Certificate Management Protocol (CMP) caches additional certificates (extraCerts) sent in a CMP message, but never expunges them (for instance if they are invalid). If a server reuses an OSSL_CMP_CTX frequently, this cache of extraCerts may grow unboundedly, and a malicious client may flood a CMP server with requests driving this growth. Impact summary: Users utilizing a CMP server that reuses a single OSSL_CMP_CTX for the lifetime of a server process may observe unbounded memory growth in the event a malicious client repeatedly sends requests containing unique extra certificates, which may lead to OOM conditions. CWE: CWE-770: Allocation of Resources Without Limits or Throttling Description: If a remote user sends CMP messages to a server with a list of extraCerts and the message is rejected, the extraCerts from the message remains in the server contexts untrusted certificate stack. This exposes servers with long lived ctx objects to Denial of Service attacks in which an attacker sends messages intending to be rejected with a large list of additional certificates repeatedly, forcing the server to store them indefinitely. The issue was fixed by removing the added extra certs if the message is rejected, using the same method as when the context is configured to not do caching at all. FIPS impact: no As the CMP code lives outside the FIPS module boundary, no FIPS modules are affected by this CVE.
- BDU:2026-14718
- EUVD-2026-65484
- ALSA-2026:67154
- ALSA-2026:67165
- openSUSE-SU-2026:11623-1
- openSUSE-SU-2026:21744-1
- RHSA-2026:67154
- RHSA-2026:67165
- RLSA-2026:67154
- RLSA-2026:67165
- SUSE-SU-2026:23463-1
- SUSE-SU-2026:23473-1
- SUSE-SU-2026:23512-1
- SUSE-SU-2026:23609-1
- SUSE-SU-2026:3866-1
- SUSE-SU-2026:3876-1
- SUSE-SU-2026:4032-1
- SUSE-SU-2026:4039-1
- Published
- Aug 25, 2026
- Updated
- Sep 11, 2026
- EPSS
- 0.5% · 48th percentile
- CWE
- CWE-770
Report tools
Action score
23
Monitor
Low priority for now.
- CVSS
- 23 / 40 · 5.9 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.5%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| openssl | openssl | cpe:2.3:a:openssl:openssl |
Check your server's TLS configuration
The OpenSSL version can't be seen from outside; the free SSL checker tests your certificate, enabled TLS versions and weak ciphers. Confirm the version on your server with the package manager.
Run the SSL checkAffected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- openssl openssl3.0.0 and later · before 3.0.22
- openssl openssl3.4.0 and later · before 3.4.7
- openssl openssl3.5.0 and later · before 3.5.8
- openssl openssl3.6.0 and later · before 3.6.4
- openssl openssl4.0.0 and later · before 4.0.2
Versions reported by the vendor
Affected version ranges reported by the assigning authority (openssl). Independent of NVD's CPE analysis and usually ahead of it.
OpenSSL OpenSSL
- 4.0.0 and later · before 4.0.2affected · semver
- 3.6.0 and later · before 3.6.4affected · semver
- 3.5.0 and later · before 3.5.8affected · semver
- 3.4.0 and later · before 3.4.7affected · semver
- 3.0.0 and later · before 3.0.22affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:10 | openssl | before 1:3.5.8-1.el10_2.alma.1 | 1:3.5.8-1.el10_2.alma.1 |
| AlmaLinux:10 | openssl-devel | before 1:3.5.8-1.el10_2.alma.1 | 1:3.5.8-1.el10_2.alma.1 |
| AlmaLinux:10 | openssl-libs | before 1:3.5.8-1.el10_2.alma.1 | 1:3.5.8-1.el10_2.alma.1 |
| AlmaLinux:10 | openssl-perl | before 1:3.5.8-1.el10_2.alma.1 | 1:3.5.8-1.el10_2.alma.1 |
| AlmaLinux:9 | openssl | before 1:3.5.8-1.el9_8 | 1:3.5.8-1.el9_8 |
| AlmaLinux:9 | openssl-devel | before 1:3.5.8-1.el9_8 | 1:3.5.8-1.el9_8 |
| AlmaLinux:9 | openssl-libs | before 1:3.5.8-1.el9_8 | 1:3.5.8-1.el9_8 |
| AlmaLinux:9 | openssl-perl | before 1:3.5.8-1.el9_8 | 1:3.5.8-1.el9_8 |
| Alpine:v3.22 | openssl | from 3.0.0 · before 3.5.8-r0 | 3.5.8-r0 |
| Debian:12 | openssl | before 3.0.22-1~deb12u1 | 3.0.22-1~deb12u1 |
| Debian:13 | openssl | before 3.5.7-1~deb13u2 | 3.5.7-1~deb13u2 |
| Debian:14 | openssl | before 3.6.4-1 | 3.6.4-1 |
| openSUSE:Leap 16.0 | openssl-3 | before 3.5.0-160000.10.1 | 3.5.0-160000.10.1 |
| openSUSE:Tumbleweed | openssl-3 | before 3.5.3-8.1 | 3.5.3-8.1 |
| Red Hat:enterprise_linux:10.2 | openssl | before 1:3.5.8-1.el10_2 | 1:3.5.8-1.el10_2 |
| Red Hat:enterprise_linux:10.2 | openssl-debuginfo | before 1:3.5.8-1.el10_2 | 1:3.5.8-1.el10_2 |
| Red Hat:enterprise_linux:10.2 | openssl-debugsource | before 1:3.5.8-1.el10_2 | 1:3.5.8-1.el10_2 |
| Red Hat:enterprise_linux:10.2 | openssl-devel | before 1:3.5.8-1.el10_2 | 1:3.5.8-1.el10_2 |
| Red Hat:enterprise_linux:10.2 | openssl-libs | before 1:3.5.8-1.el10_2 | 1:3.5.8-1.el10_2 |
| Red Hat:enterprise_linux:10.2 | openssl-libs-debuginfo | before 1:3.5.8-1.el10_2 | 1:3.5.8-1.el10_2 |
| Red Hat:enterprise_linux:10.2 | openssl-perl | before 1:3.5.8-1.el10_2 | 1:3.5.8-1.el10_2 |
| Red Hat:enterprise_linux:9::appstream | openssl-debuginfo | before 1:3.5.8-1.el9_8 | 1:3.5.8-1.el9_8 |
| Red Hat:enterprise_linux:9::appstream | openssl-debugsource | before 1:3.5.8-1.el9_8 | 1:3.5.8-1.el9_8 |
| Red Hat:enterprise_linux:9::appstream | openssl-devel | before 1:3.5.8-1.el9_8 | 1:3.5.8-1.el9_8 |
+13
Same product
openssl: all recordsOther highest-scoring records for the same primary product.
- CVE-2014-0160The (1) TLS and (2) DTLS implementations in OpenSSL 1.0.1 before 1.0.1g do not properly handle Heartbeat Extension packets, which allows remKEV90Now
- CVE-2021-3711SM2 Decryption Buffer Overflow65This week
- CVE-2003-0545Double free vulnerability in OpenSSL 0.9.7 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code 65This week
Published before and after this one in the same product
- ← EarlierCVE-2026-63072Aug 25, 2026 · Heap Buffer Overflow in CMS Key Unwrapping30Monitor
- ← EarlierCVE-2026-63073Aug 25, 2026 · Untrusted Sender DN Used as Format String in CMP Response Validation39Monitor
- Later →CVE-2026-63075Aug 25, 2026 · QUIC ACK-only Packet Retention Can Cause Memory Exhaustion30Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| OpenSSL OpenSSL | 3.0.22 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.4.7 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.5.8 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.6.4 | Vendor (CNA) |
| OpenSSL OpenSSL | 4.0.2 | Vendor (CNA) |
| azl3 edk2 20240524git3e722403cd16-18 on Azure Linux 3.0 | 20240524git3e722403cd16-19 | Microsoft (MSRC) |
| azl3 edk2 20240524git3e722403cd16-20 on Azure Linux 3.0 | 20240524git3e722403cd16-19 | Microsoft (MSRC) |
| azl3 openssl 3.3.7-4 on Azure Linux 3.0 | 3.3.7-6 | Microsoft (MSRC) |
| azl3 openssl 3.3.7-6 on Azure Linux 3.0 | 3.3.7-6 | Microsoft (MSRC) |
| almalinux:openssl | 1:3.5.8-1.el10_2.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:openssl-devel | 1:3.5.8-1.el10_2.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:openssl-libs | 1:3.5.8-1.el10_2.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:openssl-perl | 1:3.5.8-1.el10_2.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| alpine:openssl | 3.5.8-r0 · Alpine:v3.22 | Package registry (OSV) |
| debian:openssl | 3.0.22-1~deb12u1 · Debian:12 | Package registry (OSV) |
| opensuse:openssl-3 | 3.5.3-8.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:openssl | 1:3.5.8-1.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:openssl-debuginfo | 1:3.5.8-1.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:openssl-debugsource | 1:3.5.8-1.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:openssl-devel | 1:3.5.8-1.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:openssl-libs | 1:3.5.8-1.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:openssl-libs-debuginfo | 1:3.5.8-1.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| red hat:openssl-perl | 1:3.5.8-1.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
| rocky linux:openssl | 1:3.5.8-1.el10_2 · Rocky Linux:10 | Package registry (OSV) |
| suse:openssl-3 | 3.5.0-160000.10.1 · SUSE:Linux Micro 6.2 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- Neil Hormanremediation developer
- Pavоl Žáčik (Red Hat)reporter
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-630750 days apartQUIC ACK-only Packet Retention Can Cause Memory Exhaustion30Monitor
- CVE-2026-1445612 days apartUnbounded Memory Growth in QUIC Server Incoming Channel Queue30Monitor
- CVE-2026-5487335 days apartQUIC STREAM Fragment Metadata DoS30Monitor
- CVE-2026-8478435 days apartQUIC: Unbounded RETIRE_CONNECTION_ID Backlog30Monitor
- CVE-2026-3518935 days apartExcessive Memory Allocation in Relative CRLDP Processing21Monitor
- CVE-2026-7580435 days apartQUIC Connection-Level Flow Control is Not Enforced for Streams21Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-770 · Allocation of Resources Without Limits or ThrottlingCVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- FloodingCAPEC-125likelihood: High · Medium
- Excessive AllocationCAPEC-130likelihood: Medium · Medium
- XML Ping of the DeathCAPEC-147likelihood: Low · Medium
- Exponential Data ExpansionCAPEC-197likelihood: High · Medium
- Serialized Data Parameter BlowupCAPEC-229likelihood: High · High
- Serialized Data with Nested PayloadsCAPEC-230likelihood: Medium · High
- Oversized Serialized Data PayloadsCAPEC-231likelihood: Medium · High
- HTTP DoSCAPEC-469Low
ATT&CK techniques
- Network Denial of Service:Direct Network FloodT1498.001
- Network Denial of Service:Reflection AmplificationT1498.002
- Endpoint Denial of ServiceT1499
- Endpoint Denial of Service: OS Exhaustion FloodT1499.001
- Endpoint Denial of Service:Service Exhaustion FloodT1499.002
- Endpoint Denial of Service:Application Exhaustion FloodT1499.003
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (5 more)Show less
- github.com/openssl/openssl/commit/21a5d9658b0c66daace60e10ea18ff32a448de9f
- github.com/openssl/openssl/commit/74ae7f6df47a5767c1010b88c47507dfc5b32c46
- github.com/openssl/openssl/commit/75360af9650d4e0c82ba0050c5c9912cd79e54af
- github.com/openssl/openssl/commit/f636f9ca0fa1bae5b42f9e787f025c96fb09c43a
- openssl-library.org/news/secadv/20260825.txt
Vendor advisories and official records. Exploit/PoC links are deliberately left out.