Bug 2500041 (CVE-2026-59886)

Summary:	CVE-2026-59886 pyasn1: pyasn1: Denial of Service via crafted ASN.1 REAL values
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	alinfoot, amctagga, anpicker, anthomas, aoconnor, aprice, aruklets, bbrownin, bniver, bparees, cmyers, dfreiber, dnakabaa, doconnor, drow, dschmidt, dtrifiro, dymurray, eborisov, ebourniv, eglynn, ehelms, flucifre, ggainey, gmeno, gparvin, groman, hasun, ibolton, ilpinto, jburrell, jdobes, jfula, jjoyce, jlanda, jmatthew, jmitchel, jmontleo, jowilson, jpasqual, jpretori, jsamir, jschluet, juwatts, jwong, kaycoth, kbempah, kgaikwad, kshier, lball, lcouzens, lgallett, lhh, ltomasbo, mbenjamin, mburns, mgarciac, mhackett, mhulan, mrunge, ngough, nmoumoul, nyancey, oezr, omaciel, ometelka, orabin, osousa, pakotvan, pcreech, pgaikwad, ptisnovs, rbryant, rchan, rhaigner, rhel-process-autobot, rjohnson, sbunciak, simaishi, slucidi, smallamp, solenoci, sostapov, sseago, stcannon, sthirugn, syedriko, teagle, tmalecek, ttakamiy, vereddy, veshanka, vimartin, vkumar, watson-tool-maintainers, weaton, xdharmai, yguenane, ykashtan
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A remote attacker can exploit this by providing specially crafted BER/CER/DER-encoded ASN.1 data with a large exponent in the REAL value. When the application subsequently prints, logs, compares, or performs arithmetic on the decoded value, this can cause excessive CPU and memory consumption, leading to a denial of service (DoS).	Story Points:	---
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Documentation:	---	CRM:
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2501248, 2501686, 2501687, 2501688
Bug Blocks:

Description OSIDB Bzimport 2026-07-14 17:01:42 UTC

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the univ.Real type converted its mantissa, base, and exponent value to a Python float using exact big-integer exponentiation. A BER, CER, or DER encoded REAL value only a few bytes long can carry a very large exponent, causing float conversion through prettyPrint(), str(), comparison, arithmetic, int(), or an explicit float() call to consume excessive CPU and memory and hang applications that decode untrusted ASN.1 data and then print, log, or compare decoded objects. This issue is fixed in version 0.6.4.