CVE-2026-20889Public exploitNetwork attack vector

Code execution via overflowing X3F thumbnail dimensions

Published Apr 7, 2026 · Updated Apr 7, 2026

Heap buffer overflow in LibRaw commit d20315b allows remote attackers to corrupt memory by supplying a crafted X3F thumbnail. x3f_thumb_loader multiplies attacker-controlled columns and rows in 32-bit arithmetic, passes the truncated size to malloc, then writes rows past the undersized buffer with memmove. Reachability requires an application to call unpack_thumb on the file and a LibRaw build compiled with USE_X3FTOOLS, which is disabled by default; a successful overwrite corrupts the heap and enables code execution.

CVSS severity9.8
Critical
EPSS probability0.80%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in LibRaw commit d20315b allows remote attackers to corrupt memory by supplying a crafted X3F thumbnail. x3f_thumb_loader multiplies attacker-controlled columns and rows in 32-bit arithmetic, passes the truncated size to malloc, then writes rows past the undersized buffer with memmove. Reachability requires an application to call unpack_thumb on the file and a LibRaw build compiled with USE_X3FTOOLS, which is disabled by default; a successful overwrite corrupts the heap and enables code execution.

The record

CVE
CVE-2026-20889
Published
Apr 7, 2026
Updated
Apr 7, 2026
Vendor
LibRaw LLC
Product
LibRaw
Classifications
CWE-120, CWE-190, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Commit d20315b

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

LibRaw LLC · LibRawversion=Commit d20315b

Published CVSS scores

7.7SUSECVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
7.5SUSECVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
7.5Amazon LinuxCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
7.5Red HatCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
9.8Cisco TalosCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input
CWE-190Integer Overflow or Wraparound
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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