Bug 2397617 (CVE-2025-6921)

Summary: CVE-2025-6921 transformers: Regular Expression Denial of Service (ReDoS) in huggingface/transformers
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: alinfoot, anpicker, bbrownin, bparees, dtrifiro, haoli, hasun, hkataria, jajackso, jcammara, jfula, jkoehler, jmitchel, jneedle, jowilson, jwong, kegrant, koliveir, kshier, lphiri, mabashia, nyancey, ometelka, pbraun, ptisnovs, rbryant, shvarugh, simaishi, smcdonal, stcannon, syedriko, teagle, tfister, thavo, ttakamiy, weaton, xdharmai, yguenane
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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The huggingface/transformers library, is vulnerable to a Regular Expression Denial of Service (ReDoS) in the AdamWeightDecay optimizer. The vulnerability arises from the _do_use_weight_decay method, which processes user-controlled regular expressions in the include_in_weight_decay and exclude_from_weight_decay lists. Malicious regular expressions can cause catastrophic backtracking during the re.search call, leading to 100% CPU utilization and a denial of service. This issue can be exploited by attackers who can control the patterns in these lists, potentially causing the machine learning task to hang and rendering services unresponsive.
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Description OSIDB Bzimport 2025-09-23 14:01:28 UTC 
The huggingface/transformers library, versions prior to 4.53.0, is vulnerable to Regular Expression Denial of Service (ReDoS) in the AdamWeightDecay optimizer. The vulnerability arises from the _do_use_weight_decay method, which processes user-controlled regular expressions in the include_in_weight_decay and exclude_from_weight_decay lists. Malicious regular expressions can cause catastrophic backtracking during the re.search call, leading to 100% CPU utilization and a denial of service. This issue can be exploited by attackers who can control the patterns in these lists, potentially causing the machine learning task to hang and rendering services unresponsive.