NVD / CVE Program· CNA redhat

CVE-2018-16870: It was found that wolfssl before 3.15.7 is vulnerable to a new variant of the Bleichenbacher attack to perform downgrade attacks against TLS

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: 1.5% (FIRST EPSS); higher than 75.4% 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: wolfssl (Debian:12) 4.1.0+dfsg-1.

Low priority for now. Upgrade to wolfssl (Debian:12) 4.1.0+dfsg-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

It was found that wolfssl before 3.15.7 is vulnerable to a new variant of the Bleichenbacher attack to perform downgrade attacks against TLS. This may lead to leakage of sensible data.

MediumCVSS 5.9 · v3.0—No exploit Fix available

Published: Jan 3, 2019
Updated: Jun 16, 2026
EPSS: 1.5% · 75th percentile
CWE: CWE-200

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 23 / 40 · 5.9 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 1.5%

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.

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

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 help

Affected 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
wolfssl	wolfssl	cpe:2.3:a:wolfssl:wolfssl

Check your server's TLS configuration

The wolfSSL 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 check

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

wolfssl wolfsslbefore 3.15.7

Versions reported by the vendor

Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.

n/a wolfssl
- before 3.15.7affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	wolfssl	before 4.1.0+dfsg-1	4.1.0+dfsg-1

Same product

wolfssl: all records

Other highest-scoring records for the same primary product.

CVE-2017-13099wolfSSL Bleichenbacher/ROBOT
60This week
CVE-2019-11873wolfSSL 4.0.0 has a Buffer Overflow in DoPreSharedKeys in tls13.c when a current identity size is greater than a client identity size.
42Plan
CVE-2017-2800A specially crafted x509 certificate can cause a single out of bounds byte overwrite in wolfSSL through 3.10.2 resulting in potential certif
42Plan

Published before and after this one in the same product

← EarlierCVE-2014-2903Oct 6, 2017 · CyaSSL does not check the key usage extension in leaf certificates, which allows remote attackers to spoof servers via a crafted server cert
23Monitor
← EarlierCVE-2018-12436Jun 14, 2018 · wolfcrypt/src/ecc.c in wolfSSL before 3.15.1.patch allows a memory-cache side-channel attack on ECDSA signatures, aka the Return Of the Hidd
18Monitor
Later →CVE-2019-6439Jan 15, 2019 · examples/benchmark/tls_bench.c in a benchmark tool in wolfSSL through 3.15.7 has a heap-based buffer overflow.
40Plan

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
debian:wolfssl	4.1.0+dfsg-1 · Debian:12	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.

EPSS, last 120 days

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.

wolfSSL/wolfsslPR 1950

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

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: high · data can be read
Integrity: none
Availability: none

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: None
Availability impact: None

Weakness class (CWE)

CWE-200 · Exposure of Sensitive Information to an Unauthorized Actor

CVSS vector

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

nvd-primary

Root cause

The extension requests broader permissions than its function needs and sends the data it collects out for purposes beyond its stated function.

The bug in code

The whole CWE-200 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

json

1{
2  "permissions": ["tabs", "<all_urls>"],
3  "background": { "service_worker": "analytics.js" }
4}

Fixed

json

1{
2  "permissions": ["activeTab"],
3  "host_permissions": ["https://yildiz.example/*"]
4}

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)

ATT&CK techniques

Change log

Fix✗ → ✓Sep 28, 2026, 10:48 PM UTC

For records you follow, these changes also arrive as notifications. →

References

cat.eyalro.net/

Show all references (1 more)

github.com/wolfSSL/wolfssl/pull/1950

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records