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VulnerabilityPublished Updated

CVE-2019-12900: bzip2 · Out-of-bounds Write

Source CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
7.9% chance of exploitation in 30 days – higher than 94% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jun 2019

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Debianbzip2pkg:deb/bzip2Other threatsAffected
  • <=1.0.6
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

  1. Immediate patching: Apply official patches or updates to the bzip2 library as soon as they become available. Monitor vendor advisories for embedded products that include bzip2 and update accordingly.
  2. Input validation and filtering: Implement strict validation on all incoming compressed data streams to detect and block suspicious or malformed bzip2 archives, especially those with an unusually high number of selectors.
  3. Use alternative compression methods: Where feasible, replace bzip2 with more secure or actively maintained compression libraries that do not have known critical vulnerabilities.
  4. Network segmentation and filtering: Restrict exposure of systems that decompress bzip2 data to untrusted networks. Use firewalls and intrusion detection systems to monitor and block anomalous decompression requests.
  5. Runtime protections: Employ memory protection mechanisms such as Address Space Layout Randomization (ASLR), Data Execution Prevention (DEP), and stack canaries to mitigate exploitation impact.
  6. Monitoring and incident response: Establish logging and alerting for decompression failures or crashes related to bzip2 usage to detect potential exploitation attempts early.
  7. Vendor coordination: Engage with software and hardware vendors to ensure timely patching of embedded bzip2 components in their products.

Description

BZ2_decompress in decompress.c in bzip2 through 1.0.6 has an out-of-bounds write when there are many selectors.

References

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