Bug 2513510 (CVE-2026-18503)

Summary: CVE-2026-18503 python: Python: Denial of Service via super-linear regular expression work in csv.Sniffer.sniff()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: abarbaro, adinn, agarcial, akostadi, akoudelk, alebedev, alinfoot, alizardo, amasferr, amctagga, anpicker, ansmith, anthomas, anujha, aoconnor, aprice, aruklets, asegurap, asoldano, ataylor, bbaranow, bbrownin, bmaxwell, bniver, bparees, brasmith, bstansbe, cahl, cdrage, cmyers, cochase, crizzo, dakwon, derez, dfreiber, dhanak, dkeler, dlofthou, dmayorov, dnakabaa, doconnor, dranck, drosa, drow, dschmidt, dsimansk, dtrifiro, dymurray, eborisov, ebourniv, echaudro, eglynn, ehelms, ehugonne, fleitner, flucifre, fzakkak, galder, gbenhaim, ggainey, gmeno, gparvin, groman, gtanzill, hasun, ibolton, ilpinto, istudens, ivassile, iweiss, jbritton, jburrell, jbuscemi, jchui, jdobes, jfula, jhe, jjoyce, jlanda, jlledo, jmatthew, jmitchel, jmontleo, jowilson, jpasqual, jpretori, jsamir, jschluet, juwatts, jwong, kaycoth, kbempah, kgaikwad, kingland, kshier, ktraynor, ktsao, lball, lbragsta, lbrazdil, lcouzens, lhh, ljawale, ltomasbo, mbabacek, mbarnett, mbenjamin, mburns, mdellweg, mgarciac, mhackett, mhayden, mhulan, mkleinhe, mminar, mnovotny, mosmerov, mrunge, msilmser, msvehla, nboldt, ngough, niyer, nmoumoul, nwallace, nyancey, oaljalju, oezr, olubyans, omaciel, ometelka, orabin, osousa, pakotvan, pantinor, pberan, pcreech, pesilva, pgaikwad, pjindal, pmackay, prwatson, psrna, ptisnovs, rbiba, rbryant, rchan, rekumar, rhaigner, rhel-process-autobot, rjohnson, rkhan, rstancel, rushinde, sakbas, sausingh, sbiarozk, sbunciak, sdawley, sdoran, sgehwolf, simaishi, slucidi, smallamp, solenoci, sostapov, sseago, sskracic, stcannon, sthirugn, suppawar, syedriko, teagle, thason, thjenkin, tmalecek, tpfromme, tqvarnst, tsedmik, ttakamiy, twaugh, vdosoudi, vereddy, veshanka, vimartin, vkumar, vvoronko, watson-tool-maintainers, weaton, wenshen, xdharmai, xiaoxwan, yguenane, ykashtan, zzhou
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the `csv.Sniffer.sniff()` function within Python. An attacker can exploit this by providing specially crafted CSV samples, which can trigger super-linear regular-expression processing during dialect sniffing. This excessive processing consumes significant CPU resources, potentially leading to a Denial of Service (DoS) for applications that process unbounded input using this function.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-08-10 14:11:32 UTC 
Attacker-controlled CSV samples can trigger super-linear 
regular-expression work during dialect sniffing and consume significant 
CPU when applications pass unbounded input to csv.Sniffer.sniff().