CVE-2023-6237: Excessive time spent checking invalid RSA public keys
Noroxi assessment
Priority: Monitor (action score 24/100)
- 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: 2.3% (FIRST EPSS); higher than 83.2% of all records.
- 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 3.0.13, 3.1.5, 3.2.1; Azure Linux 3.0 ARM 20.14.0-1, 3.3.0-1, 38.0.72.2-1; Azure Linux 3.0 x64 20.14.0-1, 3.3.0-1, 38.0.72.2-1.
Low priority for now. Upgrade to OpenSSL OpenSSL 3.0.13, 3.1.5, 3.2.1; Azure Linux 3.0 ARM 20.14.0-1, 3.3.0-1, 38.0.72.2-1; Azure Linux 3.0 x64 20.14.0-1, 3.3.0-1, 38.0.72.2-1 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: Checking excessively long invalid RSA public keys may take a long time. Impact summary: Applications that use the function EVP_PKEY_public_check() to check RSA public keys may experience long delays. Where the key that is being checked has been obtained from an untrusted source this may lead to a Denial of Service. When function EVP_PKEY_public_check() is called on RSA public keys, a computation is done to confirm that the RSA modulus, n, is composite. For valid RSA keys, n is a product of two or more large primes and this computation completes quickly. However, if n is an overly large prime, then this computation would take a long time. An application that calls EVP_PKEY_public_check() and supplies an RSA key obtained from an untrusted source could be vulnerable to a Denial of Service attack. The function EVP_PKEY_public_check() is not called from other OpenSSL functions however it is called from the OpenSSL pkey command line application. For that reason that application is also vulnerable if used with the '-pubin' and '-check' options on untrusted data. The OpenSSL SSL/TLS implementation is not affected by this issue. The OpenSSL 3.0 and 3.1 FIPS providers are affected by this issue.
- Published
- Apr 25, 2024
- Updated
- Oct 14, 2026
- EPSS
- 2.3% · 83th percentile
- CWE
- CWE-606
Report tools
Action score
24
Monitor
Low priority for now.
- CVSS
- 23 / 40 · 5.9 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 2.3%
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.
—
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 checkVersions 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
- 3.0.0 and later · before 3.0.13affected · semver
- 3.1.0 and later · before 3.1.5affected · semver
- 3.2.0 and later · before 3.2.1affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:9 | edk2-aarch64 | before 20240524-6.el9_5 | 20240524-6.el9_5 |
| AlmaLinux:9 | edk2-ovmf | before 20240524-6.el9_5 | 20240524-6.el9_5 |
| AlmaLinux:9 | edk2-tools | before 20240524-6.el9_5 | 20240524-6.el9_5 |
| AlmaLinux:9 | edk2-tools-doc | before 20240524-6.el9_5 | 20240524-6.el9_5 |
| AlmaLinux:9 | openssl | before 1:3.0.7-27.el9 | 1:3.0.7-27.el9 |
| AlmaLinux:9 | openssl-devel | before 1:3.0.7-27.el9 | 1:3.0.7-27.el9 |
| AlmaLinux:9 | openssl-libs | before 1:3.0.7-27.el9 | 1:3.0.7-27.el9 |
| AlmaLinux:9 | openssl-perl | before 1:3.0.7-27.el9 | 1:3.0.7-27.el9 |
| Alpine:v3.17 | openssl | before 3.0.12-r3 | 3.0.12-r3 |
| Alpine:v3.18 | openssl | before 3.1.4-r4 | 3.1.4-r4 |
| Debian:12 | openssl | before 3.0.13-1~deb12u1 | 3.0.13-1~deb12u1 |
| Debian:13 | openssl | before 3.1.5-1 | 3.1.5-1 |
| openSUSE:Leap 15.5 | openssl-3 | before 3.0.8-150500.5.24.1 | 3.0.8-150500.5.24.1 |
| openSUSE:Leap Micro 5.3 | openssl-3 | before 3.0.8-150400.4.49.1 | 3.0.8-150400.4.49.1 |
| openSUSE:Tumbleweed | openssl-3 | before 3.1.4-3.1 | 3.1.4-3.1 |
| Red Hat:enterprise_linux:9::appstream | edk2 | before 0:20240524-6.el9_5 | 0:20240524-6.el9_5 |
| Red Hat:enterprise_linux:9::appstream | edk2-aarch64 | before 0:20240524-6.el9_5 | 0:20240524-6.el9_5 |
| Red Hat:enterprise_linux:9::appstream | edk2-ovmf | before 0:20240524-6.el9_5 | 0:20240524-6.el9_5 |
| Red Hat:enterprise_linux:9::appstream | openssl-debuginfo | before 1:3.0.7-27.el9 | 1:3.0.7-27.el9 |
| Red Hat:enterprise_linux:9::appstream | openssl-debugsource | before 1:3.0.7-27.el9 | 1:3.0.7-27.el9 |
| Red Hat:enterprise_linux:9::appstream | openssl-devel | before 1:3.0.7-27.el9 | 1:3.0.7-27.el9 |
| Red Hat:enterprise_linux:9::appstream | openssl-libs-debuginfo | before 1:3.0.7-27.el9 | 1:3.0.7-27.el9 |
| Red Hat:enterprise_linux:9::appstream | openssl-perl | before 1:3.0.7-27.el9 | 1:3.0.7-27.el9 |
| Red Hat:enterprise_linux:9::baseos | openssl | before 1:3.0.7-27.el9 | 1:3.0.7-27.el9 |
+8
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-2024-0727Jan 26, 2024 · PKCS12 Decoding crashes23Monitor
- ← EarlierCVE-2024-2511Apr 8, 2024 · Unbounded memory growth with session handling in TLSv1.339Monitor
- Later →CVE-2024-4603May 16, 2024 · Excessive time spent checking DSA keys and parameters21Monitor
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 | 3.0.13 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.1.5 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.2.1 | Vendor (CNA) |
| Azure Linux 3.0 ARM | 20.14.0-1 · nodejs | Microsoft (MSRC) |
| Azure Linux 3.0 ARM | 3.3.0-1 · openssl | Microsoft (MSRC) |
| Azure Linux 3.0 ARM | 38.0.72.2-1 · cloud-hypervisor-cvm | Microsoft (MSRC) |
| Azure Linux 3.0 x64 | 20.14.0-1 · nodejs | Microsoft (MSRC) |
| Azure Linux 3.0 x64 | 3.3.0-1 · openssl | Microsoft (MSRC) |
| Azure Linux 3.0 x64 | 38.0.72.2-1 · cloud-hypervisor-cvm | Microsoft (MSRC) |
| CBL Mariner 2.0 ARM | 1.0.1-6 · hvloader | Microsoft (MSRC) |
| CBL Mariner 2.0 ARM | 18.20.2-1 · nodejs18 | Microsoft (MSRC) |
| CBL Mariner 2.0 ARM | 38.0.72.2-1 · cloud-hypervisor-cvm | Microsoft (MSRC) |
| CBL Mariner 2.0 x64 | 1.0.1-6 · hvloader | Microsoft (MSRC) |
| CBL Mariner 2.0 x64 | 18.20.2-1 · nodejs18 | Microsoft (MSRC) |
| CBL Mariner 2.0 x64 | 38.0.72.2-1 · cloud-hypervisor-cvm | Microsoft (MSRC) |
| almalinux:edk2-aarch64 | 20240524-6.el9_5 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:edk2-ovmf | 20240524-6.el9_5 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:edk2-tools | 20240524-6.el9_5 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:edk2-tools-doc | 20240524-6.el9_5 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:openssl | 1:3.0.7-27.el9 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:openssl-devel | 1:3.0.7-27.el9 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:openssl-libs | 1:3.0.7-27.el9 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:openssl-perl | 1:3.0.7-27.el9 · AlmaLinux:9 | Package registry (OSV) |
| alpine:openssl | 3.0.12-r3 · Alpine:v3.17 | Package registry (OSV) |
| debian:openssl | 3.0.13-1~deb12u1 · Debian:12 | Package registry (OSV) |
| opensuse:openssl-3 | 3.0.8-150500.5.24.1 · openSUSE:Leap 15.5 | Package registry (OSV) |
| red hat:edk2 | 0:20240524-6.el9_5 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:edk2-aarch64 | 0:20240524-6.el9_5 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
| red hat:edk2-debugsource | 0:20240524-6.el9_5 · Red Hat:enterprise_linux:9::crb | Package registry (OSV) |
| red hat:edk2-ovmf | 0:20240524-6.el9_5 · Red Hat:enterprise_linux:9::appstream | Package registry (OSV) |
+10
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.
- OSS-Fuzzfinder
- Tomas Mrazremediation developer
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2023-3446281 days apartExcessive time spent checking DH keys and parameters23Monitor
- CVE-2023-5678171 days apartExcessive time spent in DH check / generation with large Q parameter value22Monitor
- CVE-2023-3817269 days apartExcessive time spent checking DH q parameter value22Monitor
- CVE-2024-460321 days apartExcessive time spent checking DSA keys and parameters21Monitor
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-606 · Unchecked Input for Loop ConditionCVSS 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.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (9 more)Show less
- github.com/openssl/openssl/commit/18c02492138d1eb8b6548cb26e7b625fb2414a2a
- github.com/openssl/openssl/commit/a830f551557d3d66a84bbb18a5b889c640c36294
- www.openssl.org/news/secadv/20240115.txt
- www.openwall.com/lists/oss-security/2024/03/11/1
- security.netapp.com/advisory/ntap-20240531-0007/
- cert-portal.siemens.com/productcert/html/ssa-265688.html
- cert-portal.siemens.com/productcert/html/ssa-331112.html
- cert-portal.siemens.com/productcert/html/ssa-769027.html
- cert-portal.siemens.com/productcert/html/ssa-915275.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.