openssl-src NULL pointer Dereference in signature_algorithms processingGHSA-83mx-573x-5rw9
MEDIUMGHSA-83mx-573x-5rw9 is a medium-severity (CVSS 5.9) NULL Pointer Dereference vulnerability in openssl-src. 3 public exploit references exist, so weaponization risk is real. A fix is available for openssl-src — see the affected versions and patch details below.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-83mx-573x-5rw9 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 CVEs with a current EPSS score, this one falls in the 50–90% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
openssl-srcReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
An OpenSSL TLS server may crash if sent a maliciously crafted renegotiation ClientHello message from a client. If a TLSv1.2 renegotiation ClientHello omits the signature_algorithms extension (where it was present in the initial ClientHello), but includes a signature_algorithms_cert extension then a NULL pointer dereference will result, leading to a crash and a denial of service attack. A server is only vulnerable if it has TLSv1.2 and renegotiation enabled (which is the default configuration). OpenSSL TLS clients are not impacted by this issue. All OpenSSL 1.1.1 versions are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1k. OpenSSL 1.0.2 is not impacted by this issue. Fixed in OpenSSL 1.1.1k (Affected 1.1.1-1.1.1j).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | openssl-src | all versions | 111.15.0cargo update -p openssl-src --precise 111.15.0 |
Affected Products
multi-domain management firmwarecheckpointquantum security gateway firmwarecheckpointquantum security management firmwarecheckpointdebian linuxdebianfedorafedoraprojectfreebsdfreebsdResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openssl-src, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update openssl-src to 111.15.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-83mx-573x-5rw9 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This flaw only affects OpenSSL 1.1.1, older versions are not affected.
This flaw can be mitigated by disabling TLS renegotiation on servers compiled with OpenSSL. It is enabled by default, but can be disabled for servers which do not require it and can be used to mitigate this flaw. Versions of httpd package shipped with Red Hat Enterprise Linux 8 have TLS renegotiation disabled by default.Source: Red Hat security advisory for GHSA-83mx-573x-5rw9 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| JBCS 2.4.37 SP7 | openssl | RHSA-2021:1200 |
| JBoss Core Services on RHEL 7 | jbcs-httpd24-httpd-0:2.4.37-70.jbcs.el7 | RHSA-2021:1199 |
| Red Hat Enterprise Linux 8 | openssl-1:1.1.1g-15.el8_3 | RHSA-2021:1024 |
| Red Hat Enterprise Linux 8.1 Extended Update Support | openssl-1:1.1.1c-5.el8_1 | RHSA-2021:1131 |
| Red Hat Enterprise Linux 8.2 Extended Update Support | openssl-1:1.1.1c-18.el8_2 | RHSA-2021:1063 |
| Red Hat JBoss Web Server 3.1 | openssl | RHSA-2021:1203 |
| Red Hat JBoss Web Server 3 for RHEL 7 | tomcat-native-0:1.2.23-24.redhat_24.ep7.el7 | RHSA-2021:1202 |
| Red Hat JBoss Web Server 5 | see advisory | RHSA-2021:1196 |
Frequently Asked Questions
Is GHSA-83mx-573x-5rw9 in your dependencies?
Find it across crates.io, including transitive dependencies.