Bug 2500204 (CVE-2026-59884)

Summary:	CVE-2026-59884 python-pyasn1: pyasn1: Denial of Service via crafted BER input
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	alinfoot, amctagga, anpicker, anthomas, aoconnor, aprice, aruklets, bbrownin, bniver, 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, 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 flaw was found in pyasn1, a generic ASN.1 library for Python. The Basic Encoding Rules (BER) decoder, used by CER and DER codecs, processes long-form tags by accumulating continuation octets without an upper bound. A remote attacker can exploit this by providing a specially crafted input, leading to the construction of an arbitrarily large integer. This can cause the CPU cost to grow quadratically, resulting in a Denial of Service (DoS) for any application decoding untrusted BER, CER, or DER input.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-07-14 18:08:12 UTC

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.