CVE-2023-5363 | Incorrect cipher key & IV length processing

Issue summary: A bug has been identified in the processing of key and initialisation vector (IV) lengths. This can lead to potential truncation or overruns during the initialisation of some symmetric ciphers. Impact summary: A truncation in the IV can result in non-uniqueness, which could result in loss of confidentiality for some cipher modes. When calling EVP_EncryptInit_ex2(), EVP_DecryptInit_ex2() or EVP_CipherInit_ex2() the provided OSSL_PARAM array is processed after the key and IV have been established. Any alterations to the key length, via the "keylen" parameter or the IV length, via the "ivlen" parameter, within the OSSL_PARAM array will not take effect as intended, potentially causing truncation or overreading of these values. The following ciphers and cipher modes are impacted: RC2, RC4, RC5, CCM, GCM and OCB. For the CCM, GCM and OCB cipher modes, truncation of the IV can result in loss of confidentiality. For example, when following NIST's SP 800-38D section 8.2.1 guidance for constructing a deterministic IV for AES in GCM mode, truncation of the counter portion could lead to IV reuse. Both truncations and overruns of the key and overruns of the IV will produce incorrect results and could, in some cases, trigger a memory exception. However, these issues are not currently assessed as security critical. Changing the key and/or IV lengths is not considered to be a common operation and the vulnerable API was recently introduced. Furthermore it is likely that application developers will have spotted this problem during testing since decryption would fail unless both peers in the communication were similarly vulnerable. For these reasons we expect the probability of an application being vulnerable to this to be quite low. However if an application is vulnerable then this issue is considered very serious. For these reasons we have assessed this issue as Moderate severity overall. The OpenSSL SSL/TLS implementation is not affected by this issue. The OpenSSL 3.0 and 3.1 FIPS providers are not affected by this because the issue lies outside of the FIPS provider boundary. OpenSSL 3.1 and 3.0 are vulnerable to this issue.

Published: 2023-10-25 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2023-5363 is rated Moderate Risk (57.5/100): CVSS High severity, with medium exploitation likelihood (EPSS 3.33%). Mandatory action: Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-5363

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 6.31% 3.33% -2.98%
2 2026-06-09 6.47% 6.31% -0.16%
3 2026-05-27 6.47%

Full EPSS history (61 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-5363

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
3.9 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2023-5363

GitHub Security Advisory for CVE-2023-5363

GHSA-xw78-pcr6-wrg8 · Severity: high — Issue summary: A bug has been identified in the processing of key and initialisation vector (IV)...

OS Trackers for CVE-2023-5363

vendor priority summary link
alpine CVE-2023-5363: 1 source package rows (openssl); 84 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 7, open 77. https://security.alpinelinux.org/vuln/CVE-2023-5363
debian unimportant CVE-2023-5363 unimportant priority: Debian including 1 source packages (openssl), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-5363
redhat medium https://access.redhat.com/security/cve/CVE-2023-5363
suse high CVE-2023-5363 severity important: SUSE including 79 source package names (compat-openssl098, libopenssl-1_0_0-devel, …), 426 product×package rows across 55 product lines (SUSE CaaS Platform 4.0, SUSE Enterprise Storage 7.1, … (55 product lines)): Known Not Affected 363, Fixed 63. https://www.suse.com/security/cve/CVE-2023-5363/
ubuntu medium CVE-2023-5363 medium priority: Ubuntu including 4 source packages (edk2, nodejs, openssl, openssl1.0), 48 status rows across 12 suites (bionic, focal, jammy, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 25, DNE 10, released 7, needs-triage 4, ignored 1, needed 1. https://ubuntu.com/security/CVE-2023-5363

Affected software / configurations for CVE-2023-5363

Vendor Product Version Raw CPE
openssl openssl >= 3.0.0, < 3.0.12 cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
openssl openssl >= 3.1.0, < 3.1.4 cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
debian debian_linux 12.0 cpe:2.3:o:debian:debian_linux:12.0:*:*:*:*:*:*:*
netapp h300s_firmware cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*
netapp h410s_firmware cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:*
netapp h500s_firmware cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*
netapp h700s_firmware cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:*
netapp h410c_firmware cpe:2.3:o:netapp:h410c_firmware:-:*:*:*:*:*:*:*

References for CVE-2023-5363

URL Tags
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=0df40630850fb2740e6be6890bb905d3fc623b2d Mailing List Patch Third Party Advisory
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=5f69f5c65e483928c4b28ed16af6e5742929f1ee Patch Vendor Advisory
https://www.openssl.org/news/secadv/20231024.txt Vendor Advisory
http://www.openwall.com/lists/oss-security/2023/10/24/1
https://security.netapp.com/advisory/ntap-20231027-0010/
https://security.netapp.com/advisory/ntap-20240201-0003/
https://security.netapp.com/advisory/ntap-20240201-0004/
https://security.netapp.com/advisory/ntap-20241108-0002/
https://www.debian.org/security/2023/dsa-5532
https://cert-portal.siemens.com/productcert/html/ssa-082556.html
https://cert-portal.siemens.com/productcert/html/ssa-093430.html
https://cert-portal.siemens.com/productcert/html/ssa-277137.html
https://cert-portal.siemens.com/productcert/html/ssa-331112.html
https://cert-portal.siemens.com/productcert/html/ssa-769027.html
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