CVE-2026-5450
A public proof of concept exists; no exploitation attested.
- Published2026-04-20
- WeaknessCWE-122 · CWE-787
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
Calling the scanf family of functions with a %mc (malloc'd character match) in the GNU C Library version 2.7 to version 2.43 with a format width specifier with an explicit width greater than 1024 could result in a one byte heap buffer overflow.
Timeline
dates in UTC- 2026-04-2021:16CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 21:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-5450?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-5450?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 2.x | ≥ 2.7, ≤ 2.43 | no fix published | NVD |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Packages
- glibcAlmaLinux:10all versions · fixed in 2.39-126.el10_2.alma.1and 220 other packages
- glibcAlmaLinux:9all versions · fixed in 2.34-272.el9_8and 214 other packages
- glibcAlmaLinux:8all versions · fixed in 2.28-251.el8_10.38and 213 other packages
Vendor advisories
glibc: glibc: Heap Buffer Overflow in `scanf` with `%mc` format specifier and large width
compat-glibc-headers as a component of Red Hat Enterprise Linux 6 · compat-glibc.src as a component of Red Hat Enterprise Linux 6
Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.17.2
Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.18.2
Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.18.2
Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.18.2
Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.18.2
33 more advisories
Fix
- Vendor fix Red Hat Product Security RHSA-2026:82888 · 1 productBefore applying this update, make sure all previously released errata relevant to your system have been applied. The steps to apply the upgraded images are different depending on the installation plan approval policy you used when installing the cert-manager Operator for Red Hat OpenShift. - If t…
- Vendor fix Red Hat Product Security RHSA-2026:74674 · 1 productFor more information visit https://access.redhat.com/errata/RHSA-2026:74674
- Vendor fix Red Hat Product Security RHSA-2026:59831 · 1 productFor OpenShift Container Platform 4.12 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
- Vendor fix Red Hat Product Security RHSA-2026:60019 · 4 productsFor OpenShift Container Platform 4.17 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
- Vendor fix Red Hat Product Security RHSA-2026:56853 · 4 productsFor OpenShift Container Platform 4.16 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
- Vendor fix Red Hat Product Security RHSA-2026:57483 · 4 productsFor OpenShift Container Platform 4.18 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
- CISA-ADPSSVC decisionpoc2026-04-21
- OpenCVESSVC decisionpoc—
- CISA-ADPCVSS 3.19.82026-04-21
- CNAweakness (CWE)CWE-122read 2026-10-23
- NVDweakness (CWE)CWE-787read 2026-10-23
- FIRST EPSSEPSS score0.7 %2026-10-23
- OSVaffected packages—
- Microsoft MSRCadvisory—
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Published
- 2026-04-20
- Last Modified
- 2026-07-14
- NVD status
- Modified
- MSRC Title
- scanf %mc off-by-one heap buffer overflow
Frequently asked questions
What is CVE-2026-5450?
Is CVE-2026-5450 actively exploited?
What is the CVSS score for CVE-2026-5450?
Running glibc? Hear about its next vulnerability
Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».
No credit card required · No monthly cap on website lookups · 250 API requests/month
Go further
- Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
- Running this software? Vulnerability monitoring alerts you to new vulnerabilities in your products.
Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.