CVE-2026-28388: NULL Pointer Dereference When Processing a Delta CRL
Noroxi assessment
Priority: Monitor (action score 30/100)
- 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: 0.88% (FIRST EPSS); higher than 59.2% 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. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: OpenSSL OpenSSL 3.0.20, 3.3.7, 3.4.5; azl3 openssl 3.3.5-4 on Azure Linux 3.0 3.3.5-5; cbl2 edk2 20230301gitf80f052277c8-47 on CBL-Mariner 2.0 Release Notes.
Low priority for now. Upgrade to OpenSSL OpenSSL 3.0.20, 3.3.7, 3.4.5; azl3 openssl 3.3.5-4 on Azure Linux 3.0 3.3.5-5; cbl2 edk2 20230301gitf80f052277c8-47 on CBL-Mariner 2.0 Release Notes 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: When a delta CRL that contains a Delta CRL Indicator extension is processed a NULL pointer dereference might happen if the required CRL Number extension is missing. Impact summary: A NULL pointer dereference can trigger a crash which leads to a Denial of Service for an application. When CRL processing and delta CRL processing is enabled during X.509 certificate verification, the delta CRL processing does not check whether the CRL Number extension is NULL before dereferencing it. When a malformed delta CRL file is being processed, this parameter can be NULL, causing a NULL pointer dereference. Exploiting this issue requires the X509_V_FLAG_USE_DELTAS flag to be enabled in the verification context, the certificate being verified to contain a freshestCRL extension or the base CRL to have the EXFLAG_FRESHEST flag set, and an attacker to provide a malformed CRL to an application that processes it. The vulnerability is limited to Denial of Service and cannot be escalated to achieve code execution or memory disclosure. For that reason the issue was assessed as Low severity according to our Security Policy. The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.
- BDU:2026-10553
- openSUSE-SU-2026:10533-1
- openSUSE-SU-2026:20525-1
- RHSA-2026:7261
- SUSE-SU-2026:1213-1
- SUSE-SU-2026:1214-1
- SUSE-SU-2026:1215-1
- SUSE-SU-2026:1216-1
- SUSE-SU-2026:1255-1
- SUSE-SU-2026:1256-1
- SUSE-SU-2026:1257-1
- SUSE-SU-2026:1290-1
- SUSE-SU-2026:1291-1
- SUSE-SU-2026:1375-1
- SUSE-SU-2026:1386-1
- SUSE-SU-2026:1577-1
- SUSE-SU-2026:21037-1
- SUSE-SU-2026:21065-1
- SUSE-SU-2026:21107-1
- SUSE-SU-2026:21186-1
- Published
- Apr 7, 2026
- Updated
- Oct 15, 2026
- EPSS
- 0.8% · 59th percentile
- CWE
- CWE-476
Report tools
Action score
30
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.8%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- 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 openssl1.0.2 and later · before 1.0.2zp
- openssl openssl1.1.1 and later · before 1.1.1zg
- openssl openssl3.0.0 and later · before 3.0.20
- openssl openssl3.3.0 and later · before 3.3.7
- openssl openssl3.4.0 and later · before 3.4.5
- openssl openssl3.5.0 and later · before 3.5.6
- openssl openssl3.6.0 and later · before 3.6.2
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
- 3.6.0 and later · before 3.6.2affected · semver
- 3.5.0 and later · before 3.5.6affected · semver
- 3.4.0 and later · before 3.4.5affected · semver
- 3.3.0 and later · before 3.3.7affected · semver
- 3.0.0 and later · before 3.0.20affected · semver
- 1.1.1 and later · before 1.1.1zgaffected
- 1.0.2 and later · before 1.0.2zpaffected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.20 | openssl | from 1.0.2 · before 3.3.7-r0 | 3.3.7-r0 |
| Alpine:v3.22 | openssl | from 1.0.2 · before 3.5.6-r0 | 3.5.6-r0 |
| Debian:12 | openssl | before 3.0.19-1~deb12u2 | 3.0.19-1~deb12u2 |
| Debian:13 | openssl | before 3.5.5-1~deb13u2 | 3.5.5-1~deb13u2 |
| Debian:14 | openssl | before 3.6.2-1 | 3.6.2-1 |
| openSUSE:Leap 15.6 | openssl-1_0_0 | before 1.0.2p-150000.3.105.1 | 1.0.2p-150000.3.105.1 |
| openSUSE:Leap 15.6 | openssl-3 | before 3.1.4-150600.5.45.1 | 3.1.4-150600.5.45.1 |
| openSUSE:Leap 16.0 | openssl-3 | before 3.5.0-160000.7.1 | 3.5.0-160000.7.1 |
| openSUSE:Tumbleweed | openssl-3 | before 3.5.3-4.1 | 3.5.3-4.1 |
| Red Hat:hummingbird:1 | openssl | before 0:3.5.6-0.1.hum1 | 0:3.5.6-0.1.hum1 |
| Red Hat:hummingbird:1 | openssl-config-fips | before 0:3.5.6-0.1.hum1 | 0:3.5.6-0.1.hum1 |
| Red Hat:hummingbird:1 | openssl-devel | before 0:3.5.6-0.1.hum1 | 0:3.5.6-0.1.hum1 |
| Red Hat:hummingbird:1 | openssl-devel-engine | before 0:3.5.6-0.1.hum1 | 0:3.5.6-0.1.hum1 |
| Red Hat:hummingbird:1 | openssl-libs | before 0:3.5.6-0.1.hum1 | 0:3.5.6-0.1.hum1 |
| Red Hat:hummingbird:1 | openssl-perl | before 0:3.5.6-0.1.hum1 | 0:3.5.6-0.1.hum1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | openssl-3 | before 3.0.8-150500.5.60.1 | 3.0.8-150500.5.60.1 |
| SUSE:Linux Enterprise Micro 5.2 | openssl-1_1 | before 1.1.1d-150200.11.109.1 | 1.1.1d-150200.11.109.1 |
| SUSE:Linux Enterprise Micro 5.3 | openssl-1_1 | before 1.1.1l-150400.7.90.1 | 1.1.1l-150400.7.90.1 |
| SUSE:Linux Enterprise Micro 5.3 | openssl-3 | before 3.0.8-150400.4.81.1 | 3.0.8-150400.4.81.1 |
| SUSE:Linux Enterprise Micro 5.5 | openssl-1_1 | before 1.1.1l-150500.17.51.1 | 1.1.1l-150500.17.51.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | openssl-1_1 | before 1.1.1w-150700.11.16.1 | 1.1.1w-150700.11.16.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | openssl-3 | before 3.2.3-150700.5.31.1 | 3.2.3-150700.5.31.1 |
| SUSE:Linux Enterprise Module for Legacy 15 SP7 | openssl-1_0_0 | before 1.0.2p-150000.3.108.1 | 1.0.2p-150000.3.108.1 |
| SUSE:Linux Enterprise Module for Legacy 15 SP7 | openssl-1_0_0 | before 1.0.2p-150000.3.105.1 | 1.0.2p-150000.3.105.1 |
+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-2026-28386Apr 7, 2026 · Out-of-bounds Read in AES-CFB-128 on X86-64 with AVX-512 Support30Monitor
- ← EarlierCVE-2026-28387Apr 7, 2026 · Potential Use-after-free in DANE Client Code32Monitor
- Later →CVE-2026-28389Apr 7, 2026 · Possible NULL Dereference When Processing CMS KeyAgreeRecipientInfo30Monitor
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 | 3.0.20 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.3.7 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.4.5 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.5.6 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.6.2 | Vendor (CNA) |
| azl3 openssl 3.3.5-4 on Azure Linux 3.0 | 3.3.5-5 · CBL-Mariner Releases | Microsoft (MSRC) |
| cbl2 edk2 20230301gitf80f052277c8-47 on CBL-Mariner 2.0 | Release Notes | Microsoft (MSRC) |
| cbl2 hvloader 1.0.1-18 on CBL-Mariner 2.0 | Release Notes | Microsoft (MSRC) |
| cbl2 openssl 1.1.1k-39 on CBL Mariner 2.0 | 1.1.1k-40 · CBL-Mariner Releases | Microsoft (MSRC) |
| cbl2 openssl 1.1.1k-39 on CBL-Mariner 2.0 | 1.1.1k-40 · Release Notes | Microsoft (MSRC) |
| alpine:openssl | 3.3.7-r0 · Alpine:v3.20 | Package registry (OSV) |
| debian:openssl | 3.0.19-1~deb12u2 · Debian:12 | Package registry (OSV) |
| opensuse:openssl-1_0_0 | 1.0.2p-150000.3.105.1 · openSUSE:Leap 15.6 | Package registry (OSV) |
| opensuse:openssl-3 | 3.1.4-150600.5.45.1 · openSUSE:Leap 15.6 | Package registry (OSV) |
| red hat:openssl | 0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:openssl-config-fips | 0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:openssl-devel | 0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:openssl-devel-engine | 0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:openssl-libs | 0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:openssl-perl | 0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| suse:openssl-1_0_0 | 1.0.2p-150000.3.105.1 · SUSE:Linux Enterprise Module for Legacy 15 SP7 | Package registry (OSV) |
| suse:openssl-1_0_0 | 1.0.2p-3.106.1 · SUSE:Linux Enterprise Server 12 SP5-LTSS | Package registry (OSV) |
| suse:openssl-1_1 | 1.1.1d-150200.11.109.1 · SUSE:Linux Enterprise Micro 5.2 | Package registry (OSV) |
| suse:openssl-3 | 3.0.8-150500.5.60.1 · SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | Package registry (OSV) |
| suse:openssl-3 | 3.1.4-150600.5.45.1 · SUSE:Linux Enterprise Server 15 SP6-LTSS | 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.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-283890 days apartPossible NULL Dereference When Processing CMS KeyAgreeRecipientInfo30Monitor
- CVE-2026-283900 days apartPossible NULL Dereference When Processing CMS KeyTransportRecipientInfo30Monitor
- CVE-2026-4276463 days apartNULL Pointer Dereference in QUIC Server Initial Packet Handling30Monitor
- CVE-2026-4276563 days apartNULL Dereference in Certificate Verification with OCSP Checking30Monitor
- CVE-2025-6942170 days apartNULL Pointer Dereference in PKCS12_item_decrypt_d2i_ex function30Monitor
- CVE-2026-14457140 days apartRPK Server Signature Algorithm Selection Can Dereference a Missing Certificate30Monitor
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.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-476 · NULL Pointer DereferenceCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvd-primary
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 (7 more)Show less
- github.com/openssl/openssl/commit/5a0b4930779cd2408880979db765db919da55139
- github.com/openssl/openssl/commit/602542f2c0c2d5edb47128f93eac10b62aeeefb3
- github.com/openssl/openssl/commit/a9d187dd1000130100fa7ab915f8513532cb3bb8
- github.com/openssl/openssl/commit/d3a901e8d9f021f3e67d6cfbc12e768129862726
- openssl-library.org/news/secadv/20260407.txt
- cert-portal.siemens.com/productcert/html/ssa-032379.html
- cert-portal.siemens.com/productcert/html/ssa-265688.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.