Vulnerability · Published Apr 20, 2026 · Assigned by glibc

CVE-2026-5450scanf %mc off-by-one heap buffer overflow

Critical 9.8

In plain English

A critical-severity heap buffer overflow in glibc from The GNU C Library. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.8Critical
Exploit odds (30 days)0.5%top 56.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:8compat-libpthread-nonshared2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:10glibc2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-all-langpacks2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-all-langpacks2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-all-langpacks2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-benchtests2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-benchtests2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-benchtests2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-common2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-common2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-common2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-devel2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-devel2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-devel2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-doc2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-doc2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-doc2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-gconv-extra2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-gconv-extra2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-gconv-extra2.34-272.el9_8ALSA-2026:33226
AlmaLinux:8glibc-headers2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-headers2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-aa2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-aa2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-aa2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-af2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-af2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-af2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-agr2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-agr2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-agr2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-ak2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-ak2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-ak2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-am2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-am2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-am2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-an2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-an2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-an2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-anp2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-anp2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-anp2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-ar2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-ar2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-ar2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-as2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-as2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-as2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-ast2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-ast2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-ast2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-ayc2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-ayc2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-ayc2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-az2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-az2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-az2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-be2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-be2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-be2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-bem2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-bem2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-bem2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-ber2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-ber2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-ber2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-bg2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-bg2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-bg2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-bhb2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-bhb2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-bhb2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-bho2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-bho2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-bho2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-bi2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-bi2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-bi2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-bn2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-bn2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-bn2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-bo2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-bo2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-bo2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-br2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-br2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-br2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-brx2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-brx2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-brx2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-bs2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-bs2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-bs2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-byn2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-byn2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-byn2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-ca2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-ca2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-ca2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-ce2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-ce2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-ce2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-chr2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-chr2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-chr2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-ckb2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:9glibc-langpack-ckb2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-cmn2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-cmn2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-cmn2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-crh2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-crh2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-crh2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-cs2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-cs2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-cs2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-csb2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-csb2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-csb2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-cv2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-cv2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-cv2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-cy2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-cy2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-cy2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-da2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-da2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-da2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-de2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-de2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-de2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-doi2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-doi2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-doi2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-dsb2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-dsb2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-dsb2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-dv2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-dv2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-dv2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-dz2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-dz2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-dz2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-el2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-el2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-el2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-en2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-en2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-en2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-eo2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-eo2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-eo2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-es2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-es2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-es2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-et2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-et2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-et2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-eu2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-eu2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-eu2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-fa2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-fa2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-fa2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-ff2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-ff2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-ff2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-fi2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-fi2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-fi2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-fil2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-fil2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-fil2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-fo2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-fo2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-fo2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-fr2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-fr2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-fr2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-fur2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-fur2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-fur2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-fy2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-fy2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-fy2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-ga2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-ga2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-ga2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-gbm2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:10glibc-langpack-gd2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-gd2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-gd2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-gez2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-gez2.28-251.el8_10.38ALSA-2026:33126
AlmaLinux:9glibc-langpack-gez2.34-272.el9_8ALSA-2026:33226
AlmaLinux:10glibc-langpack-gl2.39-126.el10_2.alma.1ALSA-2026:33092
AlmaLinux:8glibc-langpack-gl2.28-251.el8_10.38ALSA-2026:33126

Affected products (as reported)

VendorProductVersions
The GNU C Library glibc 2.7 – before *

Weakness: CWE-122 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References