Bug 2448857 (CVE-2026-31972)

Summary: CVE-2026-31972 samtools: SAMtools: Information Disclosure and Denial of Service via use-after-free vulnerability in mpileup command
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in SAMtools. During the `mpileup` command, data could be prematurely discarded, leading to an attempt to read from memory that has already been freed. This use-after-free vulnerability may allow for the disclosure of sensitive program state information or cause the program to crash, resulting in a Denial of Service (DoS).
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Bug Depends On: 2449263, 2449264, 2449265, 2449266    
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Description OSIDB Bzimport 2026-03-18 21:02:05 UTC 
SAMtools is a program for reading, manipulating and writing bioinformatics file formats. The `mpileup` command outputs DNA sequences that have been aligned against a known reference. On each output line it writes the reference position, optionally the reference DNA base at that position (obtained from a separate file) and all of the DNA bases that aligned to that position. As the output is ordered by position, reference data that is no longer needed is discarded once it has been printed out. Under certain conditions the data could be discarded too early, leading to an attempt to read from a pointer to freed memory. This bug may allow information about program state to be leaked. It may also cause a program crash through an attempt to access invalid memory. This bug is fixed in versions 1.21.1 and 1.22. There is no workaround for this issue.