VulnerabilityPublished 9 Nov 2026

CVE-2026-124077: Apache Commons Codec · Improper Neutralization of Null Byte or NUL Character

Affects Apache Commons CodecSource CVE Database V5

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Not known to be exploited : upgrade to 1.23.0 when convenient.

Data as of 9 Nov 2026, 20:20 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none

Patch: Available – fixed in 1.23.0, 87f6aa2818836998528ff4b0d1ea35545a800ee5

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 9 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Apache Commons Codec and commons-codec/commons-codec to 1.23.0; Apache Commons Codec to 87f6aa2818836998528ff4b0d1ea35545a800ee5.

Affected software

Product	Affected	Fixed in
Apache Commons Codeccommons-codec:commons-codec	Affected >=1.22.0 <1.23.0	Fixed in 1.23.0
Apache Software FoundationApache Commons Codec	Affected ≥ 387120c901f4a75c3112dfdf8877dcdec7ae685d, < 87f6aa2818836998528ff4b0d1ea35545a800ee5	Fixed in 87f6aa2818836998528ff4b0d1ea35545a800ee5
Mavencommons-codec/commons-codec`pkg:maven/commons-codec/commons-codec`Other threats	Affected >=1.22.0 <1.23.0	Fixed in 1.23.0

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

AI-suggested

Users should upgrade Apache Commons Codec to version 1.23.0 or later, where this issue is fixed. No other mitigation is required as the fix is available and addresses the vulnerability directly.

Description

A vulnerability in Apache Commons Codec versions 1.22.0 up to but not including 1.23.0 allows crafted tree entry names containing NUL bytes to cause different directory trees to serialize to the same Git tree identifier or SWHID. This occurs because the GitIdentifiers class did not reject NUL bytes in tree entry names. The impact is limited since common file systems disallow NUL bytes in file names, so only applications building trees from external sources like archive formats permitting NUL bytes (e.g., ZIP) or direct API input are affected. The issue is fixed in version 1.23.0.

Impact

The vulnerability allows two different directory trees to produce identical Git tree identifiers or SWHIDs if tree entry names contain crafted NUL bytes. This could cause confusion or integrity issues in applications relying on these identifiers for uniqueness or verification. However, the impact is limited because typical file systems do not permit NUL bytes in file names, restricting the vulnerability to applications processing names from other sources that allow NUL bytes, such as ZIP archives or direct API inputs.

CWE-158Improper Neutralization of Null Byte or NUL Character (opens in a new tab)
Variant weakness
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes NUL characters or null bytes when they are sent to a downstream component.
Developers should anticipate that null characters or null bytes will be injected/removed/manipulated in the input vectors of their product. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
OWASP ASVS 4.0.3
V1.5.1 (opens in a new tab)
V5.2.2 (opens in a new tab)
Attack patterns
Embedding NULL Bytes (opens in a new tab)
Postfix, Null Terminate, and Backslash (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 9 Nov 2026, 20:20 UTC

WeaknessesCWE-158

Technical details

References

Community reviews

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